Add xLocCustomPowerShellScript in OneLoc task

[martinrrm]

To double check:

Needed for NuGet.Client change NuGet/NuGet.Client#7259.

We use OneLoc to localize our strings, unfortunately OneLoc returns the files with BOM, and when moved to VMR BOM is removed, creating a "back and forth" PR creation between VMR and OneLoc, examples: https://github.com/NuGet/NuGet.Client/pull/7256/changes
https://github.com/NuGet/NuGet.Client/pull/7251/changes

• The right tests are in and the right validation has happened. Guidance: https://github.com/dotnet/arcade/blob/main/Documentation/Validation.md

[akoeplinger]

hmm we don't have that issue in any other repo as far as I know. Are you sure you don't have some .gitattributes setting that strips the BOM?

[martinrrm]

@akoeplinger Interesting, let me investigate that. I reach out to OneLoc folks, and this is what they suggested. Thanks!