Convert JIT\Directed tests to merged test groups (#83256)

Steps involved in conversion:
- Remove test straccess4 - identical to straccess3_cs_d
- Remove duplicate csproj files - identical to versions without _cs in their names
- Manually remove main arg from out_of_range_fp_to_int_conversions.
- Remove Main from straccess3 (save as comment for local use)
- Remove switchdefaultonly* Main argument (replace with noinline constant argument)
- Remove IL namespace/class declarations (in shift/) that break ILTransform tool
  Related PR #64837
- Use $(TestLibraryProjectPath) in 5 ilproj files (helps ILTransform)
  Related PR #66157
- Manually rename ldfldstatic1_il_r

  Actual dedup strategy groups projs in groups based on suffixes _r, _d, etc.
  This file does not have a matching _d version, which leads ILTransform to
  inconsistently renaming projects.
- [cs-main] Remove unused Main arg from arglist\vararg.cs
- [ILTransform -p] Rename _d/_r ilproj to _il_d/_il_r (but undo debuginfo/tests)
- [ILTransform -n] 3 iterations - Deduplicate project names
- [ILTransform -a] Match .assembly names to project names
- [ILTransform -prociso] Set RequiresProcessIsolation based on other attributes
- [ILTransform -collapse-main-sig] Collapse .method Main to one line to help future ILTransform passes
- [ILTransform -public] Make entry points public, add class if entrypoint is global
- Manually remove "public public" from C# (ILTransform failure on multiline declaration)
- Manually fix accessibility after exposing main class (other now-public methods with private signatures)
- Manually add missing public/class to entry points (missed by ILTransform)
- [ILTransform -sr] Fix System.Runtime references
- [ILTransform -ilfact] [Fact], Main->TestEntryPoint, no OutputType==Exe
- Add projects for merged test runners and Directory.Build.props
- Move simple test runner code to __GenerateMainWrapper.Main (avoids conflicts with Program in tests)
- Rename IL classes to avoid keywords
- Manually update issues.targets (after renaming various projects)
- Manually convert more_tails.cs (and generated IL from it)
- Manually fix punning.cs (depended on simple wrapper using "class Program")
- Finish merge - incorporate changes to csproj/Dir.B.props - fix xunit.analyzers errors
- Rename csproj to be shorter/more consistent with upcoming JIT/Regression change

Author: markples

src/tests/JIT/Directed/Arrays/Complex1.csproj

@@ -1,6 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
     <CLRTestPriority>1</CLRTestPriority>
   </PropertyGroup>
   <PropertyGroup>

src/tests/JIT/Directed/Arrays/Complex2.csproj

@@ -1,6 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
     <CLRTestPriority>1</CLRTestPriority>
   </PropertyGroup>
   <PropertyGroup>

src/tests/JIT/Directed/Arrays/LoopCloning.cs

@@ -5,10 +5,12 @@
 using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.Intrinsics;
+using Xunit;
 
 public class Program
 {
-    public static unsafe int Main()
+    [Fact]
+    public static unsafe int TestEntryPoint()
     {
         int result = 0;
         try {

src/tests/JIT/Directed/Arrays/LoopCloning.csproj

@@ -1,6 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
     <CLRTestPriority>1</CLRTestPriority>
   </PropertyGroup>
   <PropertyGroup>

src/tests/JIT/Directed/Arrays/Simple1.csproj

@@ -1,6 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
     <CLRTestPriority>1</CLRTestPriority>
   </PropertyGroup>
   <PropertyGroup>

src/tests/JIT/Directed/Arrays/Simple2.csproj

@@ -1,6 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
     <CLRTestPriority>1</CLRTestPriority>
   </PropertyGroup>
   <PropertyGroup>

src/tests/JIT/Directed/Arrays/complex1.cs

@@ -3,6 +3,7 @@
 //
 
 using System;
+using Xunit;
 
 // Do a complex 5 dimensional Jagged array.
 struct Complex
@@ -13,10 +14,11 @@ public void mul_em()
 	c = a * b;
   }
 };
-public 
-class Complex_Array_Test
+
+public class Complex_Array_Test
 {
-	public static int Main()
+	[Fact]
+	public static int TestEntryPoint()
 	{
 		Console.WriteLine("Starting...");
 		int SIZE = 10;

src/tests/JIT/Directed/Arrays/complex2.cs

@@ -3,6 +3,7 @@
 //
 
 using System;
+using Xunit;
 public struct Yak
 {
     public Int32 a;
@@ -16,13 +17,14 @@ public void Do_Something()
 }
 
 
-internal class Complex2_Array_Test
+public class Complex2_Array_Test
 {
-    public static void test(Yak[,,,,,,] Odd_Variable)
+    internal static void test(Yak[,,,,,,] Odd_Variable)
     {
         Console.Write(Odd_Variable.Length);
     }
-    public static int Main()
+    [Fact]
+    public static int TestEntryPoint()
     {
         Console.WriteLine("Starting...");
         int SIZE = 2;

src/tests/JIT/Directed/Arrays/nintindexoutofrange.cs

@@ -3,8 +3,9 @@
 //
 using System;
 using System.Runtime.CompilerServices;
+using Xunit;
 
-class NintIndexOutOfRangeTest
+public class NintIndexOutOfRangeTest
 {
     [MethodImpl(MethodImplOptions.NoInlining)]
     static void Stelem_Ref(object[] arr, nint i, Object value)
@@ -20,7 +21,8 @@ static void LdElemA(object[] arr, nint i)
         LdElemATestHelper(ref arr[i]);
     }
 
-    public static unsafe int Main()
+    [Fact]
+    public static unsafe int TestEntryPoint()
     {
         long longIndex = ((long)1) << 32;
         nint index = (nint)longIndex;

src/tests/JIT/Directed/Arrays/nintindexoutofrange.csproj

@@ -1,6 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
     <CLRTestPriority>0</CLRTestPriority>
   </PropertyGroup>
   <PropertyGroup>