buildKitVendor etc.. expansion for clang-cl support

[wchou158]

This changes user-visible behavior

The following changes are proposed:

• Added "ClangCl" to the CompilerVendorEnum type
• Enhanced vendor detection to identify Clang-cl kits by name
• Updated version detection to treat ClangCl the same as Clang (reusing the same regex)
• Fixed variable expansion for ${buildKitVendor}, ${buildKitVersionMajor}, etc., when using clang-cl-based kits on Windows

The purpose of this change

When using a clang-cl toolchain on Windows, variables like ${buildKitVendor} and ${buildKitVersionMajor} did not expand correctly in user-defined build directory paths. For example, with Cmake: Build Directory set to

${workspaceFolder}/build-${buildKitHostOs}-${buildKitVendor}${buildKitVersionMajor}-${buildKitTargetArch}-${buildType}

Before:

[cmake] -- Build files have been written to: C:/svn/myApp/build-win32-__unknown_vendor__0-unknown-Debug

After this change:

[cmake] -- Build files have been written to: C:/svn/myApp/build-win32-ClangCl20-x64-Debug

[gcampbell-msft]

Could you add a changelog update? In a new 1.22 section. Thanks!

[wchou158]

@microsoft-github-policy-service agree

[lygstate]

@wchou158 rebase and squash into a single commit