[Note] Move StopWatch.APIFormat() to convert package

[6543]

from #12458 (comment)
...

• cache Issues and Repos if convert a list of StopWatches to APIFormat ...

[6543]

same candidate:

gitea/routers/api/v1/repo/commits.go

Line 218 in f74055b

func toCommit(ctx *context.APIContext, repo *models.Repository, commit *git.Commit, userCache map[string]*models.User) (*api.Commit, error) {