Improve page fetching and allow local wiki downloads

• use wiki media api to get page source

• wip: use fetch all endpoint to get pages

• wip: fetch pages per category

• add --fast flag to allow only fetching pages without categories

• wip: add local-wiki command & change save paths to be urlencoded

• fix tests

• improve missing page file error

• use wiki media generator api to hugely improve preformance

• add local-wiki function

• multi-thread archwiki page fetching

• improve error reporting in local-wiki sub-command

• split up un-categorized data into chunks to improve local-wiki performance

• fix variable name

• evenly chunk wiki categories based on page count

• use 'sanitize_filename' to create save file names

• don't override existing wiki files by default

• move functions out of main and add doc comments

• improve help command messages

• update README