Add new Jira Connect app modal and button with groups listing

What does this MR do?

This feature is behind the feature flag new_jira_connect_ui added in !50692 (merged).

This MR adds a button and modal that lists all available groups. In a later MR, we will add the ability to link a group to the Jira connect app integration.

Screenshots (strongly suggested)

Title and button

Modal (empty state)

Modal (with namespaces)

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 #13020 (closed)