[Performance Bug] Bytecode caching in vnext uses brokered APIs to check file properties.

[stecrain]

UwpScriptStore and UwpPreparedScriptStore are using brokered (cross-process) Apis to check file properties.

These classes were introduced in PR #2653

This issue is to investigate using in-process APIs available to UWPs to get the file properties.
Really we are only interested in the last write time.

On Xbox this is a 300ms Launch penalty.

Looking in WPA even with samples it is pretty clear to see this happening.

I believe we should be able to use some form of GetFileAttributes to reduce the cost of checking the file write times.

https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfileattributesexa