Add devops adoption segment modal component

What does this MR do?

This MRs adds the devops adoption segment modal.

The modal is going to be used for adding and editing segments within the feature. First iteration will only be covering adding segments.

As the backend is not yet merged, I'm iterating on this feature by getting the modal merged with populated group data. The mutation to actually save the added group will come next 🚀

This should be totally fine as we're being a feature flag which will not yet be enabled on production!

Feature flag rollout issue: #271568 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• 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 #271247 (closed)