Expand #error version output to include compiler assembly path and use full commit SHA everywhere (#80894)

Author: Copilot

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -5460,7 +5460,7 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
     <value>Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.</value>
   </data>
   <data name="ERR_CompilerAndLanguageVersion" xml:space="preserve">
-    <value>Compiler version: '{0}'. Language version: {1}.</value>
+    <value>Compiler version: '{0}'. Language version: {1}. Compiler path: '{2}'.</value>
   </data>
   <data name="IDS_FeatureAsyncMain" xml:space="preserve">
     <value>async main</value>

src/Compilers/CSharp/Portable/Parser/DirectiveParser.cs

@@ -333,13 +333,14 @@ private DirectiveTriviaSyntax ParseErrorOrWarningDirective(SyntaxToken hash, Syn
                     if (errorText.Equals("version", StringComparison.Ordinal))
                     {
                         string version = CommonCompiler.GetProductVersion(typeof(CSharpCompiler));
+                        string assemblyPath = CommonCompiler.GetAssemblyLocation(typeof(CSharpCompiler));
                         var specified = this.Options.SpecifiedLanguageVersion;
                         var effective = specified.MapSpecifiedToEffectiveVersion();
 
                         var displayLanguageVersion = specified == effective ? specified.ToDisplayString() : $"{specified.ToDisplayString()} ({effective.ToDisplayString()})";
 
                         eod = this.AddError(eod, triviaOffset, triviaWidth, ErrorCode.ERR_CompilerAndLanguageVersion, version,
-                            displayLanguageVersion);
+                            displayLanguageVersion, assemblyPath);
                     }
                     else
                     {