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>

options/locale/locale_en-US.ini

@@ -477,6 +477,7 @@ include_error = ` must contain substring '%s'.`
 glob_pattern_error = ` glob pattern is invalid: %s.`
 regex_pattern_error = ` regex pattern is invalid: %s.`
 username_error = ` can only contain alphanumeric chars ('0-9','a-z','A-Z'), dash ('-'), underscore ('_') and dot ('.'). It cannot begin or end with non-alphanumeric chars, and consecutive non-alphanumeric chars are also forbidden.`
+invalid_group_team_map_error = ` mapping is invalid: %s`
 unknown_error = Unknown error:
 captcha_incorrect = The CAPTCHA code is incorrect.
 password_not_match = The passwords do not match.
@@ -2758,6 +2759,8 @@ auths.oauth2_required_claim_value_helper = Set this value to restrict login from
 auths.oauth2_group_claim_name = Claim name providing group names for this source. (Optional)
 auths.oauth2_admin_group = Group Claim value for administrator users. (Optional - requires claim name above)
 auths.oauth2_restricted_group = Group Claim value for restricted users. (Optional - requires claim name above)
+auths.oauth2_map_group_to_team = Map claimed groups to Organization teams. (Optional - requires claim name above)
+auths.oauth2_map_group_to_team_removal = Remove users from synchronized teams if user does not belong to corresponding group.
 auths.enable_auto_register = Enable Auto Registration
 auths.sspi_auto_create_users = Automatically create users
 auths.sspi_auto_create_users_helper = Allow SSPI auth method to automatically create new accounts for users that login for the first time