Implement React GUI

[inbarbarkai]

• [x] Created a custom Keycloak image.
• [x] Implemented authentication flow.
• [x] Fix Keycloak seed.
• Inviter:
  • [x] Implement create invitation.
  • [ ] Implement update invitation.
• Guard:
  • [ ] Implement active invitations screen.
  • [ ] Implement admit functionality.
• Admin
  • [ ] Implement users screen.
  • [ ] Implement getting event logs.
  • [ ] Implement update user infomration.
  • [ ] Implement set user role.

[inbarbarkai]

OK, the basic logic is in place. @yarons Should I wait with this PR until the entire UI is implemented or should we merge?

[yarons]

@inbarbarkai we can wait for the UI, there's no other work done in other branches anyway.

Thank you so much!