chore: use the same .golangci.yml as the runner & gofumpt over gofmt (#206)

To prepare for a smooth merge in the runner codebase.

- run with --fix for gofumpt and golangci
- manual edits for
  - disabling useless package naming warning
  - rename variables that had underscore in their name
  - remove trailing else at the end of a few functions

Reviewed-on: https://code.forgejo.org/forgejo/act/pulls/206
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

act/filecollector/file_collector.go

@@ -97,8 +97,7 @@ type Fs interface {
 	Readlink(path string) (string, error)
 }
 
-type DefaultFs struct {
-}
+type DefaultFs struct{}
 
 func (*DefaultFs) Walk(root string, fn filepath.WalkFunc) error {
 	return filepath.Walk(root, fn)