Revert "Drop BuildMetadata from NPM package version

"

This reverts commit 5e1adb5.

Fixes #943

Author: AArnott

src/NerdBank.GitVersioning/VersionOracle.cs

@@ -376,7 +376,7 @@ public IDictionary<string, string> CloudBuildVersionVars
     /// <summary>
     /// Gets the version to use for NPM packages.
     /// </summary>
-    public string NpmPackageVersion => $"{this.Version.ToStringSafe(3)}{this.PrereleaseVersion}";
+    public string NpmPackageVersion => this.SemVer2;
 
     /// <summary>
     /// Gets a SemVer 1.0 compliant string that represents this version, including the -COMMITID suffix