Multiple filters for a route and classname filter

[kenjis]

Description
Supersedes #5108

• add multiple filters for a route (disabled by default)
• add Config\Feature class for enabling multiple filters
• add classname filter
• fix doc comments

CI4 follows semantic versioning, so changes that break backward compatibility are not allowed without major version up.

The multiple filters feature breaks backward compatibility, because it uses new methods.
Therefore, it is disabled by default and users can enable it in the configuration class if they want to use it.

Users who want to use the new features will be able to set themselves up for disruptive changes.
Users of existing CI4 applications will be backward compatible through updates.

The code will be more complex, but I think it will be less complex than adding code that forces the API to handle values of different types (e.g. converting an array to CSV and set it to a string variable) on the condition that no API changes are made at all.

Checklist:

• Securely signed commits
• Component(s) with PHPdocs
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide