notifications: add submission action notifications

[rekt-hard]

actions: send notification on submission accept action

❤️ Thank you for your contribution!

Description

closes inveniosoftware/invenio-requests#339
Send notification when executing a submission request action.

Checklist

Ticks in all boxes and 🟢 on all GitHub actions status checks are required to merge:

• I'm aware of the code of conduct.
• I've created logical separate commits and followed the commit message format.
• I've added relevant test cases.
• I've added relevant documentation.
• I've marked translation strings (for relevant code).
• I've followed the CSS/JS and React guidelines (for relevant code).
• I've followed the web accessibility guidelines (for relevant code).
• I've followed the user interface guidelines (for relevant code).
• I've identified the copyright holder(s) and updated copyright headers for touched files (>15 lines contributions).
• I've NOT included third-party code (copy/pasted source code or new dependencies).

Third-party code

If you've added third-party code (copy/pasted or new dependencies), please reach out to an architect.

Reminder

By using GitHub, you have already agreed to the GitHub’s Terms of Service including that:

1. You license your contribution under the same terms as the current repository’s license.
2. You agree that you have the right to license your contribution under the current repository’s license.

[rekt-hard]

Specific accept action notification for the community submission. Other actions will follow a similar pattern.
I think accept/decline would be the same.
Expire should probably only notify the request creator. Since the action will be performed by the system, we probably do not need the identity and the identity context resolve.
For cancel, it should probably notify the community owners/curators (similar to the community submission).

[kpsherva]

if we merge this PR we will send 2 emails for access request accept action, see:
https://github.com/inveniosoftware/invenio-rdm-records/blob/master/invenio_rdm_records/requests/access/requests.py#L104
could you integrate (replace) this one with your newly defined actions notifications ?

[rekt-hard]

These notifications are specific to the community submission/inclusion actions. Do access requests and inclusion requests share the same service? If not, we should be good here.
Should we create a separate PR for replacing the mails with notifications?

[kpsherva]

These notifications are specific to the community submission/inclusion actions. Do access requests and inclusion requests share the same service? If not, we should be good here. Should we create a separate PR for replacing the mails with notifications?

OK for separate PR!

[rekt-hard]

Just tested locally and it did not send two mails/notifications on access request accept action.