Apply "excludes" for OutputFileProducer

"excludes" should be applied both SourceFileProducer and
OutputFileProducer. But we've been missing the latter.
(see android/paths_test.go)

There's one more to note. Previously, the exclusion was done by
modifying slice directly, which caused some problem(b/76179848).
The fix was returning a copy from Srcs() method. But there're still many
implementors which just return internal slices directly.

This change creates a new array when it needs to exclude something from
returned slice.

Bug: n/a
Test: m (soong test added)
Change-Id: I1ba91e490cb55fc243020681667278cdc75f59df

android/module.go

@@ -2099,15 +2099,6 @@ func (m *moduleContext) CheckbuildFile(srcPath Path) {
 	m.checkbuildFiles = append(m.checkbuildFiles, srcPath)
 }
 
-func findStringInSlice(str string, slice []string) int {
-	for i, s := range slice {
-		if s == str {
-			return i
-		}
-	}
-	return -1
-}
-
 // SrcIsModule decodes module references in the format ":name" into the module name, or empty string if the input
 // was not a module reference.
 func SrcIsModule(s string) (module string) {