Display API errors in invite modal before closing [RUN ALL RSPEC]

What does this MR do?

Adds form group validations error field inside Invite Members modal to display API errors on single invite or add before the modal closes.

• For single invitee scenarios only. Multiple failures will be dealt with separately #325147

• Partially resolves #325147

• Related to https://gitlab.com/gitlab-org/gitlab/-/issues/276399

• Related to feature flag rollout issue https://gitlab.com/gitlab-org/gitlab/-/issues/247208

• The restricted domain error message display text will be dealt with separately in !61425 (merged)

Screenshots (in progress)

After:

Before:

Invite a group:

share with group error after	before

Note: Already shared group will be removed from select dropdown results in https://gitlab.com/gitlab-org/gitlab/-/issues/332279

Test Scenarios for 'Restrict membership by email domain' Group only:

1. Enable Restrict membership by email domain under Group Settings -> General -> Permissions, LFS, 2FA

	Scenario	Expected Result
1	Invite existing member to group who has a restricted email address	Displays groups members API response message
2	Invite new email address to group using restricted email address	Displays groups invitations API response message
3	Invite new email address to project of restricted group	Displays projects invitations API response message
4	Invite existing member to project of restricted group	Displays projects members API response message

	Scenario	Expected Result
1	Invite existing member to group who has a restricted email address	Displays groups members API response message
2	Invite existing member who has a restricted email address to project created under restricted group	Displays projects members API response message
3	Invite new email address to group using restricted email address	Displays groups invitations API response message
4	Invite new email address to project created under a restricted group using restricted email address	Displays project invitations API response message

Does this MR meet the acceptance criteria?

• Feature is still behind a feature flag Feature.enable(:invite_members_group_modal) so no changelog is included.

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• Documentation (if required)
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• 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 #325147