feat(admin-gui): display all rpc errors when copying application form

Description

feat(admin-gui): display all rpc errors when copying application form

• Any RPCError that might occur after submitting application-form-copy-items-dialog will now be displayed
• Special case for MissingSubmitButtonException has been created

How to test

Run the branch locally, go to any Application form and check behaviour of some of the possible errors, notably the MissingSubmitButtonException. Some examples:

• Source group has no application form (FormNotExistsException)
• the resulting application form would contain any input item, but no submit button (MissingSubmitButtonException, possible to use group #21472 from mberky-vo as Source group with input item but no submit button). This case also needs this BE merge request to be either deployed or merged.
• To test the default behaviour for generic errors, you can make two application forms containing Groups for embedded applications and try to copy from one to the other

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

Closes STR-1532