Change some tests to be conditional on the availability of SCOSSL

[vcsjones]

Some of our cryptography tests are conditioned on whether or not they are running on Azure Linux, which by default uses SCOSSL for cryptographic algorithms. This is not guaranteed though - using vanilla OpenSSL on Azure Linux is possible simply by uninstalling the SymCrypt-OpenSSL package.

In this case, our tests would fail because they are assuming the environment is using SCOSSL when it is really using OpenSSL.

n.b. not all of our tests can be conditioned on if SCOSSL is the default OpenSSL provider. Azure Linux itself applies some patches when building OpenSSL. A notable example is they compile OpenSSL with -no-chacha. That means that regardless of the OpenSSL provider, ChaCha20Poly1305 will not be available. So some tests remain conditioned on IsAzureLinux, not IsSymCryptOpenSsl.

With SymCrypt-OpenSSL package present:

Without SymCrypt-OpenSSL package present:

Fixes #118656

[Copilot]

Pull Request Overview

This PR refactors cryptography tests to condition behavior on the actual availability of SCOSSL (SymCrypt-OpenSSL) rather than assuming it's present on Azure Linux. This improves test accuracy since Azure Linux can run with vanilla OpenSSL if the SymCrypt-OpenSSL package is uninstalled.

Key changes:

• Introduces IsSymCryptOpenSsl platform detection by checking for SymCrypt provider module files
• Replaces IsAzureLinux checks with IsSymCryptOpenSsl checks in cryptographic algorithm tests
• Maintains some Azure Linux-specific conditions for features like ChaCha20Poly1305 that are affected by Azure Linux's OpenSSL build patches

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
PlatformDetection.Unix.cs	Adds new IsSymCryptOpenSsl detection logic that checks for SymCrypt provider module files
KmacTestDriver.cs	Updates key size requirements check from Azure Linux to SymCrypt detection
HmacMD5Tests.cs	Changes MD5 support detection from Azure Linux to SymCrypt detection
HKDFTests.cs	Updates MD5 and empty key support checks to use SymCrypt detection
DefaultECDsaProvider.Unix.cs	Changes explicit curves support check from Azure Linux to SymCrypt detection
DefaultECDiffieHellmanProvider.Unix.cs	Updates explicit curves support check to use SymCrypt detection
EcDsaOpenSslProvider.cs	Simplifies explicit curves support check using new SymCrypt detection
KeyGeneration.cs	Updates RSA key generation tests to use SymCrypt detection
ECDsaFactory.cs	Changes explicit curves failure condition to use SymCrypt detection
ECDiffieHellmanFactory.cs	Updates explicit curves failure condition to use SymCrypt detection

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[bartonjs]

LGTM, modulo one incorrectly cased letter.