Add password complexity settings to admin dashboard

This issue is a sub issue of #353874 (closed).

Proposal

The current GitLab only supports modifying the length of the password，The customer suggested that many standards of the security audits will check the complexity of passwords. Password char type requirement fields will be added under the Sign-up restrictions on General Settings page to let us have the ability to customize the complexity of user password.

Changes

1. Four boolean columns should be added to application_settings table, including password_uppercase_required, password_lowercase_required, password_number_required, password_symbol_required
2. The Password complexity configuration will be added to Admin General Settings page
3. The default password input validation UX on forms will be enhanced

Implementation Steps

1. Enhance Password input field validations on frontend !85765 (merged) by @qk44077907
2. Support password complexity on backend by @mtan-gitlab !82798 (merged)
3. Add password complexity configurations under Sign-up restrictions group frontend !86852 (merged) by @qk44077907
4. Add password complexity configurations under Sign-up restrictions group backend !85763 (merged) by @mtan-gitlab

Step 1,3 and 4 are blocked by step 2. More related MRs are listed at #353874 (closed).

Screenshots or screen recordings

The following images that shows that final stage of this feature, but the frontend part is not included in this MR.

before	after	Validation from PW creation	failed validation