Update approval settings from boolean to object format

What does this MR do?

This MR updates the approval settings from boolean to object format to prepare for the backend changes in !68476 (merged).

The following changes were made:

1. Mappers updated to output object format.
2. The setting locked status is now consumed on all settings - so a 🔒 is now also rendered on group settings.
3. The setting value is now 1-way binded on checkboxes and updated with the input event.

Screenshots or Screencasts (strongly suggested)

User projects

[GDK_HOST]/root/Typeahead.Js/edit

Before	After

Projects

[GDK_HOST]/gitlab-org/gitlab-shell/edit

Before	After

Groups

[GDK_HOST]/groups/gitlab-org/-/edit

Hidden behind a development feature flag group_merge_request_approval_settings_feature_flag.

Before	After

How to setup and validate locally (strongly suggested)

1. You need a GitLab Ultimate license.
2. Enable the feature flag: echo "Feature.enable(:group_merge_request_approval_settings_feature_flag)" | rails c
3. Enable an approval setting on instance level in [GDK_HOST]/admin/push_rule.
4. In Groups > Merge request approvals in [GDK_HOST]/groups/gitlab-org/-/edit:
   • Verify that the enabled instance setting is enforced
   • Verify that group approval settings can be changed & saved (refresh to be sure)
5. In Project > Merge request approvals [GDK_HOST]/gitlab-org/gitlab-shell/edit:
   • Verify that the enabled instance setting is enforced
   • Verify that group approval settings can be changed & saved (refresh to be sure)
6. In User Project > Merge request approvals [GDK_HOST]/root/Typeahead.Js/edit:
   • Verify that the enabled instance setting is enforced
   • Verify that group approval settings can be changed & saved (refresh to be sure)

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
  • No visual change. Group approvals is hidden behind a feature flag.
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #332548 (closed)