Extract options functionality to a new class

[acicovic]

Is your feature request related to a problem?

Most if not all of our options core functionality is within the Parsely class, which is a kind of catch-all class that has been growing lately.

Describe the solution you'd like

Extract the options functionality to a dedicated Options (or similarly named) class. While we are at it, we can consider:

• Making some functions static.
• Replacing the options array with a typed object in the code. The object could still be saved as an array into the database. We currently use phpstan types for checking the correctness of this array, but this isn't without its shortcomings.

Even the simple scenario of just moving functionality outside of the Parsely class might need changes in many other places.