Flutter 3.16 and a bunch of features/changes

update to flutter 3.16
update deps and our forks (dart_vlc is now taken from main git)
bump targetSdkVersion to 34
show init state during app start on special screen
rework how item filtering works and used (fixes lags during fast scroll and loading of new pages)
added DB indexing (may cause long first start after the update for users with huge DBs)
reworked "tab with this tag exists" indication, now has "has tab with ONLY this tag, but different booru" result (orange dot)
added ability to filter snatched items and items with AI related tags
downloads drawer and handler [WIP]
moved from WillPopScope to PopScope (may be buggy, needs testing)
reworked tab selector [a bit incomplete, needs another bug and design pass + rework history viewer in the same manner]
fixed scaling bugs with notes (error in calc when fully zoomed, sample and resized images didn't scale position properly, now it takes image dimensions directly from the loaded image through exposed data in photo_view fork)
scroll to search in tagview on focus
attempt to make double tap zoom to tap position (works poorly, still needs work, see photo_view fork)
added double-tap-drag-zoom
old tag searches from booru now properly cancel when starting a new one, which fixes race condition when old results could override newer ones
fixed videos unpausing after restate when they shouldn't
thumbnails scrollbar is now interactive (fixed in inner_drawer fork, it had a container which blocked interaction)
other small fixes

NO-ob / LoliSnatcher_Droid