Fix Security Configuration enable via MR buttons [RUN AS-IF-FOSS]

What does this MR do?

Fix Security Configuration enable via MR buttons

This makes sure that the "Configure via Merge Request" button is displayed for Secret Detection in the new Security Configuration page for all tiers.

The button was not working in FOSS since the client-side mutation was only defined in EE, so that was moved to FOSS. The backend implementation of the mutation is already in FOSS.

This also ensures that a similar button is displayed for Dependency Scanning in Ultimate projects when the sec_dependency_scanning_ui_enable feature flag is enabled.

Addresses #326005 (closed) and #328426 (closed).

Draft

This is marked draft as I'm awaiting confirmation that we want this to be available in FOSS/Free.

Screenshots or Screencasts (strongly suggested)

To reproduce these screens, enable both the security_configuration_redesign and security_configuration_redesign_ee feature flags, and also conditionally enable the sec_dependency_scanning_ui_enable feature flag according to the context. Then visit Security & Compliance > Configuration.

Context	Before	After
FOSS/Free/Premium sec_dependency_scanning_ui_enable: any
Ultimate sec_dependency_scanning_ui_enable: false
Ultimate sec_dependency_scanning_ui_enable: true

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.