Feature Request: Query categories on demand

[FibreTTP]

According to your comments on the GetCategories() function, the top 100 categories on Twitch are grabbed, seemingly repeating until there are "no more": https://github.com/Zibbp/ganymede/blob/47727d4755b4b0c44112c37f23be69ad1b465987/internal/twitch/category.go#L47-L49

This does not get every category on Twitch (which is probably unreasonable anyway), as I see when trying to add categories such as Minami Lane or Town of Salem 2 to a watched channel, they are not returned in the search box at all:

There is an API endpoint for searching for categories, so it'd be great if there was also an option to search Twitch for categories in the dropdown box, something like this:

which when clicked, would query Twitch with the string currently in the text box (with a first value of like, five), then commit new categories to the database and return them to the user.