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>

modules/web/middleware/binding.go

@@ -136,6 +136,8 @@ func Validate(errs binding.Errors, data map[string]interface{}, f Form, l transl
 				data["ErrorMsg"] = trName + l.Tr("form.regex_pattern_error", errs[0].Message)
 			case validation.ErrUsername:
 				data["ErrorMsg"] = trName + l.Tr("form.username_error")
+			case validation.ErrInvalidGroupTeamMap:
+				data["ErrorMsg"] = trName + l.Tr("form.invalid_group_team_map_error", errs[0].Message)
 			default:
 				msg := errs[0].Classification
 				if msg != "" && errs[0].Message != "" {