Add the initial drawer to the compliance dashboard

What does this MR do?

This MR adds an initial drawer component to the compliance dashboard. This is being added behind the frontend development feature flag :compliance_dashboard_drawer while development is taking place.

This first MR only includes the MR title in the drawer and sets up the opening/closing functionality. Future MR's will add all the other sections and then remove this feature flag and remove all the components duplication.

Setup & testing

This requires a GitLab Ultimate license to use

1. With the feature flag disabled go to [HOST]/groups/[GROUP]/-/security/compliance_dashboard
2. Check that MR's are shown, if they aren't then you may need to merge some in the group
3. Check the MR's data appears and only the individual links are clickable

---

1. Enable the feature flag: echo "Feature.enable(:compliance_dashboard_drawer)" | rails c
2. Go to [HOST]/groups/[GROUP]/-/security/compliance_dashboard
3. Check that MR's are shown, if they aren't then you may need to merge some in the group
4. Check the MR's data appears and you can click on an MR row to show the drawer (only shows the MR's title right now)
5. Check you can close the drawer with the X in the drawer or pressing esc
6. Check you can open another MR's drawer and also swap between MR's
7. Check that the MR rows individual links still work as expected

Screenshots (strongly suggested)

Drawer disabled	Drawer enabled
Screen_Recording_2021-06-28_at_16.12.41	Screen_Recording_2021-06-28_at_16.09.51

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• 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 #299357 (closed)