Use gitrepo's clone and push when possible (#36093)

1 Move `IsRepositoryModelOrDirExist` and `CheckCreateRepository` to
service layer
2 Use `gitrepo.Pushxxx` instead of `git.Push` when possible
3 use `gitrepo.Clonexxx` instead of `gitrepo.Clone` when possible

routers/web/repo/issue_comment.go

@@ -16,6 +16,7 @@ import (
 	"code.gitea.io/gitea/models/renderhelper"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
 	"code.gitea.io/gitea/modules/htmlutil"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup/markdown"
@@ -141,8 +142,7 @@ func NewComment(ctx *context.Context) {
 
 					if prHeadCommitID != headBranchCommitID {
 						// force push to base repo
-						err := git.Push(ctx, pull.HeadRepo.RepoPath(), git.PushOptions{
-							Remote: pull.BaseRepo.RepoPath(),
+						err := gitrepo.Push(ctx, pull.HeadRepo, pull.BaseRepo, git.PushOptions{
 							Branch: pull.HeadBranch + ":" + prHeadRef,
 							Force:  true,
 							Env:    repo_module.InternalPushingEnvironment(pull.Issue.Poster, pull.BaseRepo),