Move/Clean up privacy information in Legal-Module

Related to #1769

What does this MR do?

The Legal-Module stores information in session and different other Module access them. This MR moved the Session into a new Transaction class in the Legal-Module.

• Moved Session parts into CurrentUserLegalTransactions
• Moved Logical parts from LegalController to CurrentUserLegalTransactions
• Replaced own Content-Access by ContentGateway
• Moved downgrade of user from Legal to FoodsaverGateway, so that all downgrades are in the same gateway

How confident are you it won't break things if deployed?

I think unit and acceptance test should detect it.

Links to related issues

How to test

Screenshots (if applicable)

Checklist

• added a unit test for major logic
• no unrelated changes
• asked someone for a code review
• set a "for:" label to indicate who will be affected by this change
• set the "API change" label if changes in the API are not backward compatible
• added to the next milestone (see https://gitlab.com/foodsharing-dev/foodsharing/-/milestones, unless it has a "for:Dev" label)
• added an entry to CHANGELOG.md
• added a short text in the release notes to /release-notes/YYYY-MM.md
• Once your MR has been merged, you are responsible to create a testing issue in the Beta Testing forum: https://foodsharing.de/region?bid=734&sub=forum. Please change the MRs label to "state:Beta testing".
  • Consider writing a detailed description in German.
  • Describe in a few sentences, what should be tested from a user perspective.
  • Also mention different settings (e.g. different browsers, roles, ...) how this change can be tested.
  • Be aware, that also non technical people should understand.