Switch to ocis-accounts as the user backend

[butonic]

To get access to guest accounts we will use the ocis-accounts service instead of an ldap server

part of https://github.com/owncloud/ocis-glauth/issues/13

• killed groups ... might come back when accounts supports them

• [x] implement basic auth

[butonic]

this PR kills the bridge setup because it no longer uses LDAP as the backend but ocis-accounts

possible ways forward: - implement an ocis-graph-ldap that uses ldap as the backend? - implement a new ocis-accounts-ldap that does not persist accounts itself but instead acts as a protocol translator to a real ldap server - do not directly talk to the accounts service but use ocis-glauth, which will remain read only for now

the bridge uses konnectd, which talks to ocis-glauth (with the owncloud backend) which talks to owncloud10 with the graph app. the recent changes would make konnectd talk to ocis-glauth with ocis-accounts as the backend directly. ocis-proxy would authenticate the user and look up the id in ocis-accounts. if the user is not migrated requests will be forwarded to oc10 with the openidconnect app (or we teach it the internal jwt token). ocis-graph is not necessary there, yet.

[ownclouders]

Here is an overview of what got changed by this pull request:

Complexity increasing per file
==============================
- pkg/service/v0/users.go  3
- pkg/server/http/server.go  1
- pkg/middleware/basicauth.go  3
- pkg/middleware/option.go  2

Clones added
============
- pkg/service/v0/option.go  1
- pkg/middleware/option.go  2

Clones removed
==============
+ pkg/service/v0/users.go  -2

See the complete overview on Codacy