[chore] Refactor account deleting/block logic, tidy up some other processing things (#1599)

* start refactoring account deletion

* update to use state.DB

* further messing about

* some more tidying up

* more tidying, cleaning, nice-making

* further adventures in refactoring and the woes of technical debt

* update fr accept/reject

* poking + prodding

* fix up deleting

* create fave uri

* don't log using requestingAccount.ID because it might be nil

* move getBookmarks function

* use exists query to check for status bookmark

* use deletenotifications func

* fiddle

* delete follow request notif

* split up some db functions

* Fix possible nil pointer panic

* fix more possible nil pointers

* fix license headers

* warn when follow missing (target) account

* return wrapped err when bookmark/fave models can't be retrieved

* simplify self account delete

* warn log likely race condition

* de-sillify status delete loop

* move error check due north

* warn when unfollowSideEffects has no target account

* warn when no boost account is found

* warn + dump follow when no account

* more warnings

* warn on fave account not set

* move for loop inside anonymous function

* fix funky logic

* don't remove mutual account items on block;
do make sure unfollow occurs in both directions!

internal/api/client/bookmarks/bookmarks_test.go

@@ -275,7 +275,7 @@ func (suite *BookmarkTestSuite) TestGetBookmarksNone() {
 	testUser := suite.testUsers["local_account_1"]
 
 	// Remove all bookmarks for this account.
-	if err := suite.db.DeleteWhere(context.Background(), []db.Where{{Key: "account_id", Value: testAccount.ID}}, &[]*gtsmodel.StatusBookmark{}); err != nil {
+	if err := suite.db.DeleteStatusBookmarks(context.Background(), "", testAccount.ID); err != nil {
 		suite.FailNow(err.Error())
 	}