[feature] Custom emoji updates (serve emoji via s2s api, tune db models) (#805)

* migrate emojis

* add get emoji to s2s (federation) API

* add new emoji db + cache functions

* add shortcodeDomain lookup for emojis

* check existing emojis w/cache, not w/constraints

* go fmt

* add putEmoji func

* use new db emoji funcs instead of where

* remove emojistringstotags func

* add unique constraint back in

* fix up broken migration

* update index

internal/api/s2s/emoji/emoji.go

@@ -0,0 +1,53 @@
+/*
+   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 emoji
+
+import (
+	"net/http"
+
+	"github.com/superseriousbusiness/gotosocial/internal/api"
+	"github.com/superseriousbusiness/gotosocial/internal/processing"
+	"github.com/superseriousbusiness/gotosocial/internal/router"
+	"github.com/superseriousbusiness/gotosocial/internal/uris"
+)
+
+const (
+	// EmojiIDKey is for emoji IDs
+	EmojiIDKey = "id"
+	// EmojiBasePath is the base path for serving information about Emojis eg https://example.org/emoji
+	EmojiWithIDPath = "/" + uris.EmojiPath + "/:" + EmojiIDKey
+)
+
+// Module implements the FederationModule interface
+type Module struct {
+	processor processing.Processor
+}
+
+// New returns a emoji module
+func New(processor processing.Processor) api.FederationModule {
+	return &Module{
+		processor: processor,
+	}
+}
+
+// Route satisfies the RESTAPIModule interface
+func (m *Module) Route(s router.Router) error {
+	s.AttachHandler(http.MethodGet, EmojiWithIDPath, m.EmojiGetHandler)
+	return nil
+}