Add password complexity settings on dashboard page

This issue is a sub issue of #450 (closed)

Upstream issue https://gitlab.com/gitlab-org/gitlab/-/issues/354965

Upstream frontend MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/86852 (reverted due to pipeline failure)

Upstream frontend MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/90956 ( a fixed version for https://gitlab.com/gitlab-org/gitlab/-/merge_requests/86852)

Upstream backend MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/85763

Related discussion in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/82798

Proposal

The following configuration fields should be added under the Sign-up restrictions on General Settings page.

• Password complexity config

UI

before	after