Add missing X-Total-Count and fix some related bugs (#17968)

* Add missing `X-Total-Count` and fix some related bugs

Adds `X-Total-Count` header to APIs that return a list but doesn't have it yet.
Fixed bugs:
* not returned after reporting error (39eb82446c/routers/api/v1/user/star.go (L70))
* crash with index out of bounds, API issue/issueSubscriptions

I also found various endpoints that return lists but do not apply/support pagination yet:
```
/repos/{owner}/{repo}/issues/{index}/labels
/repos/{owner}/{repo}/issues/comments/{id}/reactions
/repos/{owner}/{repo}/branch_protections
/repos/{owner}/{repo}/contents
/repos/{owner}/{repo}/hooks/git
/repos/{owner}/{repo}/issue_templates
/repos/{owner}/{repo}/releases/{id}/assets
/repos/{owner}/{repo}/reviewers
/repos/{owner}/{repo}/teams
/user/emails
/users/{username}/heatmap
```
If this is not expected, an new issue should be opened.

Closes #13043

* fmt

* Update routers/api/v1/repo/issue_subscription.go

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>

* Use FindAndCount

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: 6543 <6543@obermui.de>

services/asymkey/ssh_key_test.go

@@ -11,6 +11,7 @@ import (
 	"code.gitea.io/gitea/models/login"
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
+
 	"github.com/stretchr/testify/assert"
 )
 

services/mailer/mailer_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"code.gitea.io/gitea/modules/setting"
+
 	"github.com/stretchr/testify/assert"
 )
 

services/pull/commit_status.go

@@ -130,7 +130,7 @@ func GetPullRequestCommitStatusState(pr *models.PullRequest) (structs.CommitStat
 		return "", errors.Wrap(err, "LoadBaseRepo")
 	}
 
-	commitStatuses, err := models.GetLatestCommitStatus(pr.BaseRepo.ID, sha, db.ListOptions{})
+	commitStatuses, _, err := models.GetLatestCommitStatus(pr.BaseRepo.ID, sha, db.ListOptions{})
 	if err != nil {
 		return "", errors.Wrap(err, "GetLatestCommitStatus")
 	}

services/pull/pull.go

@@ -782,7 +782,7 @@ func getLastCommitStatus(gitRepo *git.Repository, pr *models.PullRequest) (statu
 		return nil, err
 	}
 
-	statusList, err := models.GetLatestCommitStatus(pr.BaseRepo.ID, sha, db.ListOptions{})
+	statusList, _, err := models.GetLatestCommitStatus(pr.BaseRepo.ID, sha, db.ListOptions{})
 	if err != nil {
 		return nil, err
 	}

services/webhook/main_test.go

@@ -8,8 +8,9 @@ import (
 	"path/filepath"
 	"testing"
 
-	_ "code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/models/unittest"
+
+	_ "code.gitea.io/gitea/models"
 )
 
 func TestMain(m *testing.M) {