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/context/context.go

@@ -36,7 +36,6 @@ import (
 	"code.gitea.io/gitea/modules/typesniffer"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web/middleware"
-	"code.gitea.io/gitea/services/auth"
 
 	"gitea.com/go-chi/cache"
 	"gitea.com/go-chi/session"
@@ -659,37 +658,6 @@ func getCsrfOpts() CsrfOptions {
 	}
 }
 
-// Auth converts auth.Auth as a middleware
-func Auth(authMethod auth.Method) func(*Context) {
-	return func(ctx *Context) {
-		var err error
-		ctx.Doer, err = authMethod.Verify(ctx.Req, ctx.Resp, ctx, ctx.Session)
-		if err != nil {
-			log.Error("Failed to verify user %v: %v", ctx.Req.RemoteAddr, err)
-			ctx.Error(http.StatusUnauthorized, "Verify")
-			return
-		}
-		if ctx.Doer != nil {
-			if ctx.Locale.Language() != ctx.Doer.Language {
-				ctx.Locale = middleware.Locale(ctx.Resp, ctx.Req)
-			}
-			ctx.IsBasicAuth = ctx.Data["AuthedMethod"].(string) == auth.BasicMethodName
-			ctx.IsSigned = true
-			ctx.Data["IsSigned"] = ctx.IsSigned
-			ctx.Data["SignedUser"] = ctx.Doer
-			ctx.Data["SignedUserID"] = ctx.Doer.ID
-			ctx.Data["SignedUserName"] = ctx.Doer.Name
-			ctx.Data["IsAdmin"] = ctx.Doer.IsAdmin
-		} else {
-			ctx.Data["SignedUserID"] = int64(0)
-			ctx.Data["SignedUserName"] = ""
-
-			// ensure the session uid is deleted
-			_ = ctx.Session.Delete("uid")
-		}
-	}
-}
-
 // Contexter initializes a classic context for a request.
 func Contexter(ctx context.Context) func(next http.Handler) http.Handler {
 	_, rnd := templates.HTMLRenderer(ctx)