[chore] Fixes + updates in emoji dereferencing logic (#1022)

* fix incorrect static remote url use for emojis

* warn when emoji/attachment already exists

* defer emoji postdata execution

* rename ctx to innerCtx for clarity

* warn on emoji too large

* small efficiency fix in fetchRemoteAccountEmojis

* tidy up lock+load

* lock processing emojis

* fix little fucky wucky

* this wasn't go fmted for some reason

internal/federation/dereferencing/util.go

@@ -0,0 +1,31 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package dereferencing
+
+import (
+	"context"
+)
+
+func loadAndCleanup(ctx context.Context, load func(ctx context.Context) error, cleanup func()) error {
+	// whatever happens, clean up when we're done
+	defer cleanup()
+
+	// try and load
+	return load(ctx)
+}