Support unprotected file patterns (#16395)

Fixes #16381

Note that changes to unprotected files via the web editor still cannot be pushed directly to the protected branch. I could easily add such support for edits and deletes if needed. But for adding, uploading or renaming unprotected files, it is not trivial.

* Extract & Move GetAffectedFiles to modules/git

modules/convert/convert.go

@@ -127,6 +127,7 @@ func ToBranchProtection(bp *models.ProtectedBranch) *api.BranchProtection {
 		DismissStaleApprovals:         bp.DismissStaleApprovals,
 		RequireSignedCommits:          bp.RequireSignedCommits,
 		ProtectedFilePatterns:         bp.ProtectedFilePatterns,
+		UnprotectedFilePatterns:       bp.UnprotectedFilePatterns,
 		Created:                       bp.CreatedUnix.AsTime(),
 		Updated:                       bp.UpdatedUnix.AsTime(),
 	}