* Add LDAP Key Synchronization feature

Signed-off-by: Magnus Lindvall <magnus@dnmgns.com>

* Add migration: add login source id column for public_key table

* Only update keys if needed

* Add function to only list pubkey synchronized from ldap

* Only list pub ssh keys synchronized from ldap. Do not sort strings as ExistsInSlice does it.

* Only get keys belonging to current login source id

* Set default login source id to 0

* Some minor cleanup. Add integration tests (updete dep testify)

* Add LDAP service for tests

* Add LDAP login source and test user sign-in

* Add checks to test if user data is correct

* Add LDAP user sync test

* Add failed user sign-in test