GenerateFileFromTemplate doesn't preserve execute permission

[ericstj]

• This issue is blocking
• This issue is causing unreasonable pain

I noticed when using GenerateFileFromTemplate that it doesn't preserve the execute bit if it was present on the source file. I understand why it doesn't but it might be worth preserving so that others don't trip on this.

[premun]

[async triage] Arcade debt? (#6811)

[markwilkie]

Moving to our partners tracking epic

[ericstj]

Just to note, we aren't blocked on this or anything. It's just a suggestion so that someone else might not trip over the same thing we did. Perhaps the suggestion is "consider what file attributes should be copied from the source file when applying the template".