Map OIDC groups to Orgs/Teams (#21441)

Fixes #19555

Test-Instructions:
https://github.com/go-gitea/gitea/pull/21441#issuecomment-1419438000

This PR implements the mapping of user groups provided by OIDC providers
to orgs teams in Gitea. The main part is a refactoring of the existing
LDAP code to make it usable from different providers.

Refactorings:
- Moved the router auth code from module to service because of import
cycles
- Changed some model methods to take a `Context` parameter
- Moved the mapping code from LDAP to a common location

I've tested it with Keycloak but other providers should work too. The
JSON mapping format is the same as for LDAP.


![grafik](https://user-images.githubusercontent.com/1666336/195634392-3fc540fc-b229-4649-99ac-91ae8e19df2d.png)

---------

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

templates/admin/auth/source/ldap.tmpl

@@ -52,7 +52,7 @@
 	</div>
 	<div class="field">
 		<label for="restricted_filter">{{.locale.Tr "admin.auths.restricted_filter"}}</label>
-		<input id="restricted_filter" name="admin_filter" value="{{.restricted_filter}}">
+		<input id="restricted_filter" name="restricted_filter" value="{{.restricted_filter}}">
 		<p class="help">{{.locale.Tr "admin.auths.restricted_filter_helper"}}</p>
 	</div>
 	<div class="field">