[performance] filter model and database table improvements (#4277)

- removes unnecessary fields / columns (created_at, updated_at)
- replaces filter.context_* columns with singular filter.contexts bit field which should save both struct memory and database space
- replaces filter.action string with integer enum type which should save both struct memory and database space
- adds links from filter to filter_* tables with Filter{}.KeywordIDs and Filter{}.StatusIDs fields (this also means we now have those ID slices cached, which reduces some lookups)
- removes account_id fields from filter_* tables, since there's a more direct connection between filter and filter_* tables, and filter.account_id already exists
- refactors a bunch of the filter processor logic to save on code repetition, factor in the above changes, fix a few bugs with missed error returns and bring it more in-line with some of our newer code

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4277
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

internal/processing/timeline/notification.go

@@ -59,7 +59,7 @@ func (p *Processor) NotificationsGet(
 		return util.EmptyPageableResponse(), nil
 	}
 
-	filters, err := p.state.DB.GetFiltersForAccountID(ctx, requester.ID)
+	filters, err := p.state.DB.GetFiltersByAccountID(ctx, requester.ID)
 	if err != nil {
 		err = gtserror.Newf("error getting account %s filters: %w", requester.ID, err)
 		return nil, gtserror.NewErrorInternalError(err)