More granular notification view

[kescherCode]

Is your feature request related to a problem? Please describe.
On Web, I filter out some notification types, such as favourites, boosts and reactions, only occasionally turning them back on or switching to their respective tabs. On Megalodon, I have to scroll through a bunch of these. That's rather annoying.

Describe the solution you'd like
The notification view should behave more as it does on the Glitch flavour of glitch-soc / Catstodon, where the All view can exclude certain types of notifications, with separate "views" (subtabs, ...) existing for each notification type recognized by Megalodon.

[kescherCode]

(I might make a PR for this one)