Add catalog signing for JS/XML content files

[jesuszarate]

Summary

Generate .cat (catalog) files covering all JS and XML content shipped in the NodejsTools and TestAdapter VSIXes. This fixes VS signing compliance for 32 unsigned files (31 .js + 1 .xml) flagged by the SignVerify scan.

Changes

• Nodejs/Product/ProjectAfter.targets: Add \GenerateContentCatalog\ target that enumerates JS/XML source files, generates a CDF, runs \makecat.exe\, and signs the resulting .cat with Microsoft400. Add \IncludeCatalogInVsix\ target that includes the signed .cat in the VSIX container.
• signWhiteList.txt: Remove .js and .xml exclusions so \MicroBuildCodesignVerify\ validates these files.

Payloads fixed

Payload	Files
\msvsnodejstoolsnodejstools15803041\	19 .js + 1 .xml
\msvsnodejstoolstestadapter15803041\	12 .js

How it works

1. \GenerateContentCatalog\ runs AfterTargets=Build for VSIX projects
2. Collects all .js and .xml files from template/test framework directories
3. Generates a CDF and runs makecat.exe to produce a .cat file
4. MicroBuild signs the .cat with Microsoft400 via FilesToSign
5. \IncludeCatalogInVsix\ adds the signed .cat to VSIXSourceItem before CreateVsixContainer

Bug

https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2982241

[jesuszarate]

@joj could you take a look at my PR? Thanks.