IBX-6824: Added ability to perform queries across multiple tables

[Steveb-p]

Question	Answer
JIRA issue	IBX-6824
Type	feature
Target Ibexa version	v4.6
BC breaks	no

This PR allows ExpressionVisitor to "walk" queries across multiple tables.

Current hard requirement is that those tables need to be manually joined before querying. ExpressionVisitor does not perform any checks to see if the table will be reachable (although it has access to QueryBuilder object which has data about joined tables, so it is definitely possible to both implicitly join and check those eventually).

Decided to change how ExpressionVisitor picks a strategy to use. Previously the choice was made by looking up the implementation class for DoctrineRelationshipInterface. This will quickly become difficult to manage when we would mix and match different relationship options, so I opted for a specific option property/method instead.

Checklist:

• Provided PR description.
• Tested the solution manually.
• Provided automated test coverage.
• Checked that target branch is set correctly (main for features, the oldest supported for bugs).
• Ran PHP CS Fixer for new PHP code (use $ composer fix-cs).
• Asked for a review (ping for example @ibexa/php-dev for back-end changes and/or @ibexa/javascript-dev for
  front-end changes).