[Build] Validation script for ADMX

[htcfreek]

Check on PRs if

• each admx string exists in adml.
• admx is valid xml.
• adml is a valid xml.
• each category property is added as category definition in admx.
• each supportedOn property is added as supportedOn definition in ADMX.
• generic property (class, ...) has a supported value.
• the "last changed" comment has the same or a newer version as the newest supportedOn definition.
• the registry value name doesn't exist more than one time. (Otherwise it's a copy-paste mistake.)

@crutkas
I am not sure if this is possible. But it would be a nice feature to have an ADMX check I think.

[crutkas]

Agree. Most doing a quick scan seems possible

what prompted the ask?

[htcfreek]

@crutkas
The fix PR #25162 was the cause for this idea. The PR fixes a property missed in the Registry Preview PR.

And maybe things in this repository can help us: https://github.com/microsoft/Visual-Studio-Administrative-Templates