fix: track invalid files in LocalFlags to fix global count (#10170)

Move the "invalid" bit to a local flag, making it easier to track in counts etc.

lib/scanner/walk_test.go

@@ -567,7 +567,7 @@ func TestScanOwnershipWindows(t *testing.T) {
 	}
 }
 
-func walkDir(fs fs.Filesystem, dir string, cfiler CurrentFiler, matcher *ignore.Matcher, localFlags uint32) []protocol.FileInfo {
+func walkDir(fs fs.Filesystem, dir string, cfiler CurrentFiler, matcher *ignore.Matcher, localFlags protocol.FlagLocal) []protocol.FileInfo {
 	cfg, cancel := testConfig()
 	defer cancel()
 	cfg.Filesystem = fs