Make label templates have consistent behavior and priority (#23749)

Fix https://github.com/go-gitea/gitea/issues/23715

Other related PRs:

* #23717
* #23716
* #23719

This PR is different from others, it tries to resolve the problem fundamentally (and brings more benefits)

Although it looks like some more lines are added, actually many new lines are for tests.

----

Before, the code was just "guessing" the file type and try to parse them.

<details>

![image](https://user-images.githubusercontent.com/2114189/228002245-57d58e27-1078-4da9-bf42-5bc0b264c6ce.png)

</details>

This PR:

* Always remember the original option file names, and always use correct parser for them.

* Another benefit is that we can sort the Label Templates now (before there was a map, its key order is undefined)

![image](https://user-images.githubusercontent.com/2114189/228002432-931b9f18-3908-484b-a36b-04760c9ad132.png)

routers/web/org/setting.go

@@ -246,6 +246,6 @@ func Labels(ctx *context.Context) {
 	ctx.Data["Title"] = ctx.Tr("repo.labels")
 	ctx.Data["PageIsOrgSettings"] = true
 	ctx.Data["PageIsOrgSettingsLabels"] = true
-	ctx.Data["LabelTemplates"] = repo_module.LabelTemplates
+	ctx.Data["LabelTemplateFiles"] = repo_module.LabelTemplateFiles
 	ctx.HTML(http.StatusOK, tplSettingsLabels)
 }

routers/web/repo/issue_label.go

@@ -28,7 +28,7 @@ func Labels(ctx *context.Context) {
 	ctx.Data["Title"] = ctx.Tr("repo.labels")
 	ctx.Data["PageIsIssueList"] = true
 	ctx.Data["PageIsLabels"] = true
-	ctx.Data["LabelTemplates"] = repo_module.LabelTemplates
+	ctx.Data["LabelTemplateFiles"] = repo_module.LabelTemplateFiles
 	ctx.HTML(http.StatusOK, tplLabels)
 }
 

routers/web/repo/issue_label_test.go

@@ -10,6 +10,7 @@ import (
 
 	issues_model "code.gitea.io/gitea/models/issues"
 	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/repository"
 	"code.gitea.io/gitea/modules/test"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/services/forms"
@@ -30,6 +31,7 @@ func int64SliceToCommaSeparated(a []int64) string {
 
 func TestInitializeLabels(t *testing.T) {
 	unittest.PrepareTestEnv(t)
+	assert.NoError(t, repository.LoadRepoConfig())
 	ctx := test.MockContext(t, "user2/repo1/labels/initialize")
 	test.LoadUser(t, ctx, 2)
 	test.LoadRepo(t, ctx, 2)

routers/web/repo/repo.go

@@ -132,7 +132,7 @@ func Create(ctx *context.Context) {
 
 	// Give default value for template to render.
 	ctx.Data["Gitignores"] = repo_module.Gitignores
-	ctx.Data["LabelTemplates"] = repo_module.LabelTemplates
+	ctx.Data["LabelTemplateFiles"] = repo_module.LabelTemplateFiles
 	ctx.Data["Licenses"] = repo_module.Licenses
 	ctx.Data["Readmes"] = repo_module.Readmes
 	ctx.Data["readme"] = "Default"
@@ -200,7 +200,7 @@ func CreatePost(ctx *context.Context) {
 	ctx.Data["Title"] = ctx.Tr("new_repo")
 
 	ctx.Data["Gitignores"] = repo_module.Gitignores
-	ctx.Data["LabelTemplates"] = repo_module.LabelTemplates
+	ctx.Data["LabelTemplateFiles"] = repo_module.LabelTemplateFiles
 	ctx.Data["Licenses"] = repo_module.Licenses
 	ctx.Data["Readmes"] = repo_module.Readmes