Frontend: Use jsonurl, update filtering

[macobo]

Changes

This PR refactors significant parts of the dashboard react code.

Changes include:

1. Internally representing filters in a similar manner to the backend. Related RFC: https://github.com/plausible/knowledge_base/blob/main/src/planning/rfcs/0005-filters_v2.md
   1. Note that the filters are not prefixed in the URL for the sake shorter and prettier urls.
2. Prettier URLs for filters, e.g. http://localhost:8000/dummy.site?filters=((is,country,(US)),(is,page,(/)))&labels=(US:United%2BStates)
   1. This uses jsonurl under the hood
   2. Compatibility with bookmarked links is retained. On app load, we update the url parameters in a backwards-compatible way.
3. Refactoring linking and url param handling in general to move that logic away from specific components
4. Re-writing filter modal logic to unify 'regular' and 'props' modals

Note that the FE now supports multiple filters, though the request sent to the backend does not, yet.

Testing

I've extensively tested the changes locally, but also planning on recruiting Marco to test out these changes on staging.

[ukutaht]

Looks good to me overall. I think the filters behaviour in general can be consolidated and encapsulated a bit more on the frontend to make them easier to work with. The props filter is always a snowflake that makes everything else harder.

EDIT: To be clear I think improving the filters code in general should be done in a follow-up. For now the goal is to get the new stuff functional.

I ran some manual tests myself and haven't found any bugs. We can do some more manual testing on staging next.