create WikiAPI dataclasses

- standardize requests url format and ensure parameters no longer in hardcoded url strings
- separate functionality for scraping raw data from the wiki (.scrape) and processing it (.parse) with option to combine (.build)
- in WikiCategory class, combine API calls for retrieving page titles within a category & getting subcategories of a category
- ability to go recursively through a category to get pages from all subcategories as well (`recursive=True`), with the option to create a separate list of pages for each subcategory (`group_pages=True`)
- parse starred lists within a single infobox parameter
- will create a separate dataframe for every type of infobox that appears on the set of pages
- create .json file from WikiInfobox dataframe instead of dictionaries
- added dictionary of namespaces on Fandom Wiki (plus ability to build that dict in WikiAPI base class)