feat: disable groups user is already member of on embedded

Description

How to test

1. Have perun!4425 (merged) deployed on BE
2. Create a parent group with at least two subgroups and application forms set up (or you can use mine), put the subgroups as embedded applications on the form
3. Set yourself as a member of one of the subgroups
4. Copy invitation link for the parent group to access the application form
5. The checkbox for the group you are already a member of should be disabled with tooltip informing you of the reason
6. Check the available checkboxes and see if those are correctly handle on application submission

Author's checklist

• I have followed the contribution guidelines
• This MR has been tested or does not change functionality
• I have added relevant merge request dependencies (if this MR has any)
• I have added the correct labels
• I have assigned reviewers (if any are relevant)
• I have edited the documentation (if the changes require it) or I have noted the need for the change if I do not have access to the documentation
• I have marked all introduced BREAKING CHANGES or necessary DEPLOYMENT NOTES in the commit message(s)

Reviewer's checklist

• This MR has been tested or does not change functionality
• This MR has correct commit message format

Other information

Related issues

re STR-1379