Update HiDive scraping

[Manitary]

The HiDive website change (in March I think?) broke the scraper:

• The URL changed path from /tv/show-key to /season/show-key (and changed keys to a numeric id).
• The anime page is not served directly, but contains javascript code that performs requests to obtain the real page content.

Currently there is no "real" issue since:

• The script does not crash because the old URL still gets a page, just without any anime, so it gets ignored.
• HiDive is "simul-ripped", so everything should show up timely as torrent anyway.

These changes allow to scrape releases directly from HiDive by replicating only the requests necessary to access the page contents as JSON (see the function _load_page_data); other functions and methods are updated accordingly, as well as the various regexes.

I may rewrite some parts (e.g. episode validation) eventually to be less messy

Note:

• It may be required to re-run the edit/update commands for the currently airing HiDive shows. Double check the show_key value in the Streams table for those shows, to make sure there aren't malformed entries from the current script edit/update runs.
• I'll continue monitoring the updated script throughout the season to make sure everything works, it seems fine for what is out so far. "Unhappy paths" only got minimal testing, but there should be enough error catching to prevent crashing the script.
• I added a date check like in Add date check for HIDIVE #171 but this can be foregoed entirely (I think you can just scrap the entire loop with the validation?)