Replace invite form on Members page with modal

What does this MR do?

Replaces the Invite Form on the Members pages with links to the Invite Members Modal

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/223183

• This is all behind the invite_members_group_modal feature flag https://gitlab.com/gitlab-org/gitlab/-/issues/247208 which is enabled on Staging and needs to be enabled locally to see the form replacement.

• Both the "Invite Members" and the "Invite Group" tabs are removed in this MR, but only the "Invite Members" functionality is replaced by the modal. The "Invite Group" feature will be added back in Merge Request !50701 (merged)

Screenshots (strongly suggested)

Members Page before	Members Page after

on mobile:

group members	project members

with modal open:

group	project

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 #223183