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

models/migrations/migrations.go

@@ -340,6 +340,8 @@ var migrations = []Migration{
 	NewMigration("RecreateIssueResourceIndexTable to have a primary key instead of an unique index", recreateIssueResourceIndexTable),
 	// v193 -> v194
 	NewMigration("Add repo id column for attachment table", addRepoIDForAttachment),
+	// v194 -> v195
+	NewMigration("Add Branch Protection Unprotected Files Column", addBranchProtectionUnprotectedFilesColumn),
 }
 
 // GetCurrentDBVersion returns the current db version