Clean up permissions & adjust access

System information

• Drupal Core Version: ^10.2 || ^11
• Menu Migration Version: 4.0.0-alpha2
• PHP Version: >= 8.1 && <=8.3

Problem/Motivation

Currently, the permissions that were ported from v3 and the ones that were added in v4 are not fully functional.

Steps to reproduce

1. Create a user
2. Assign him step by step the permissions and observe his access

Proposed resolution

The existing permissions should behave as follows:
1. administer menu migration -> Bypass any menu migration permission, and have access to everything.
2. administer menu migration export types -> Administer Export Types: add, edit, delete, export.
3. administer menu migration import types -> Administer Import Types: add, edit, delete, export.
4. perform export on menu migrations -> Access to the Export Types page and perform exports.
5. perform import on menu migrations -> Access to the Import Types page and perform imports.

Note: These permissions should be enough for a future stable release, but if at any point in time there's a need for more detailed permissions (e.g. export by entity, export by destination, edit at entity level etc.) feel free to open a new issue.