Fix a bug returning 404 when display a single tag with no release (#29466)

Partially caused by #29149 

When use

```go
releases, err := getReleaseInfos(ctx, &repo_model.FindReleasesOptions{
		ListOptions: db.ListOptions{Page: 1, PageSize: 1},
		RepoID:      ctx.Repo.Repository.ID,
		TagNames:    []string{ctx.Params("*")},
		// only show draft releases for users who can write, read-only users shouldn't see draft releases.
		IncludeDrafts: writeAccess,
	})
```
replace
```go
release, err := repo_model.GetRelease(ctx, ctx.Repo.Repository.ID, ctx.Params("*"))
```
It missed `IncludeTags: true,`. That means this bug will be occupied only when the release is a tag.
This PR will fix

 - Get the right tag record when it's not a release
 - Display correct tag tab but not release tag when it's a tag.
- The button will bring the tag name to the new page when it's a single tag page
- the new page will automatically hide the release target inputbox when the tag name is pre filled. This should be backport to v1.21.

templates/repo/release/list.tmpl

@@ -18,18 +18,18 @@
 					<div class="ui twelve wide column detail">
 						<div class="gt-df gt-ac gt-sb gt-fw gt-mb-3">
 							<h4 class="release-list-title gt-word-break">
-								<a href="{{$.RepoLink}}/releases/tag/{{$release.TagName | PathEscapeSegments}}">{{$release.Title}}</a>
+								{{if $.PageIsSingleTag}}{{$release.Title}}{{else}}<a href="{{$.RepoLink}}/releases/tag/{{$release.TagName | PathEscapeSegments}}">{{$release.Title}}</a>{{end}}
 								{{template "repo/commit_statuses" dict "Status" $info.CommitStatus "Statuses" $info.CommitStatuses "AdditionalClasses" "gt-df"}}
 								{{if $release.IsDraft}}
 									<span class="ui yellow label">{{ctx.Locale.Tr "repo.release.draft"}}</span>
 								{{else if $release.IsPrerelease}}
 									<span class="ui orange label">{{ctx.Locale.Tr "repo.release.prerelease"}}</span>
-								{{else}}
+								{{else if (not $release.IsTag)}}
 									<span class="ui green label">{{ctx.Locale.Tr "repo.release.stable"}}</span>
 								{{end}}
 							</h4>
 							<div>
-								{{if $.CanCreateRelease}}
+								{{if and $.CanCreateRelease (not $.PageIsSingleTag)}}
 									<a class="muted" data-tooltip-content="{{ctx.Locale.Tr "repo.release.edit"}}" href="{{$.RepoLink}}/releases/edit/{{$release.TagName | PathEscapeSegments}}" rel="nofollow">
 										{{svg "octicon-pencil"}}
 									</a>