Introduce a lookup table for objects having modified local roles.

[elioschmutz]

This PR introduces a local roles tracking table which can be used to do ad-hoc reports about modified local-roles for users or objects.

The table stores all managed roles of each principal for each object having managed custom local roles.

For TI-1540

Checklist

Everything has to be done/checked. Checked but not present means the author deemed it unnecessary.

• Changelog entry
• Link to issue (Jira or GitHub) and backlink in issue (Jira)

Only applicable should be left and checked.

• Upgrade-Steps:
  • SQL Operations do not use imported model (see docs)
  • DB-Schema migration
    • All changes on a model (columns, etc) are included in a DB-schema migration.
    • Constraint names are shorter than 30 characters (Oracle)

[lukasgraf]

Just a few comments, otherwise LGTM 👍

[elioschmutz]

@lukasgraf @buchi I've updated the PR with your suggestions. The main difference is the use of composite primary keys and the easier update implementation.