Issue templates directory (#11450)

* Issue templates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add some comments, appease the linter

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add docs and re-use dir candidates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add default labels to issue templates

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Generate swagger

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Suggested changes

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update issue.go

* Suggestions

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Extract metadata from legacy if possible

Signed-off-by: jolheiser <john.olheiser@gmail.com>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

templates/repo/issue/choose.tmpl

@@ -0,0 +1,25 @@
+{{template "base/head" .}}
+<div class="repository new issue">
+	{{template "repo/header" .}}
+	<div class="ui container">
+		<div class="navbar">
+			{{template "repo/issue/navbar" .}}
+		</div>
+		<div class="ui divider"></div>
+		{{range .IssueTemplates}}
+			<div class="ui attached segment">
+				<div class="ui two column grid">
+					<div class="column left aligned">
+						<strong>{{.Name | RenderEmojiPlain}}</strong>
+						<br/>{{.About | RenderEmojiPlain}}
+					</div>
+					<div class="column right aligned">
+						<a href="{{$.RepoLink}}/issues/new?template={{.FileName}}{{if $.milestone}}&milestone={{$.milestone}}{{end}}" class="ui green button">{{$.i18n.Tr "repo.issues.choose.get_started"}}</a>
+					</div>
+				</div>
+			</div>
+		{{end}}
+		<a href="{{.RepoLink}}/issues/new{{if .milestone}}?milestone={{.milestone}}{{end}}">{{.i18n.Tr "repo.issues.choose.blank"}}</a>
+	</div>
+</div>
+{{template "base/footer" .}}