feat(graph): Add $filter support for lastSuccessfulSignInDateTime

It is now possible to filter users based on the lastSuccessfulSignInDateTime attribute
using query filter like:
 '$filter=signInActivity/lastSuccessfulSignInDateTime le 2021-09-01T00:00:00Z'

Note: This does only work with LDAP servers actually supporting '<=' filters.
The built-in LDAP server (idm) does not support this feature.
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f