[MovieScraper] Refactor and move to job based scrapers

[bugwelle]

Just like for TV scrapers. This will allow us to have parallel scraping, parallel searches and fewer race conditions that would be possible if we move scraping to a background process (like changing the scraper's language in the settings during scraping).

Should fix:

• #1162

[bugwelle]

TODO:

• [x] Rework CustomMovieScraper
  • [x] Let it create multiple scrape jobs
• [x] Rework CustomMovieScraper handling in MovieDialog -> if a scraper needs search first, let the user select correct movie
• [x] Save select scraper language when movie is scraped
• [x] Scrape Dialog: List scrapers that need title search (doesn't match currently; also on first dialog being shown: no item listed; when changing to other scraper, text not removed)
• [x] Custom Single Movie Scraper
• [x] Custom Multi Movie Scraper

[bugwelle]

Ok, so far I think I've implemented everything. Now I need to do some testing:

• [x] Add scraper tests
• [x] Manual test
  • [x] Single movie scraping
    • [x] Load all details
      • [x] from the same scraper
      • [x] from different scrapers (custom movie scraper)
    • [x] Load no details (via settings)
  • [x] Multi movie scraping
    • [x] Load all details
      • [x] from the same scraper
      • [x] from different scrapers (custom movie scraper)
    • [x] Load no details (via settings);
      • [x] TODO: Currently still loads items? --> was the case if only one scraper was selected --> fixed