Group and project access token via AJAX

What does this MR do and why?

For group and project, display the newly created access token without the need of reloading the page. This prevents the need of storing the new access token in Redis.

• First commit: added a represent method
• Second commit: frontend changes
• Third commit: spec fixes

I suggest to be reviewed in this way.

Closes https://gitlab.com/gitlab-org/gitlab/-/issues/365241 Closes #367541 (closed)

Epic: Stop storing encrypted access tokens in Redis (&8306 - closed)

Screenshots or screen recordings

	Before	After
Success
Error

How to set up and validate locally

1. Go to a group or project settings, for example:
   • Flightjs group: https://gdk.test:3443/groups/flightjs/-/settings/access_tokens
   • flight project: https://gdk.test:3443/flightjs/Flight/-/settings/access_tokens
2. Create and delete access tokens

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.