Merge emoji and discord_file tables

Also fix duplicate reaction when reacting with custom emoji from Matrix

database/upgrades/13-merge-emoji-and-file.sqlite.sql

@@ -0,0 +1,24 @@
+-- v13: Merge tables used for cached custom emojis and attachments
+CREATE TABLE new_discord_file (
+    url       TEXT,
+    encrypted BOOLEAN,
+    mxc       TEXT NOT NULL UNIQUE,
+
+    id         TEXT,
+    emoji_name TEXT,
+
+    size            BIGINT NOT NULL,
+    width           INTEGER,
+    height          INTEGER,
+    mime_type       TEXT NOT NULL,
+    decryption_info jsonb,
+    timestamp       BIGINT NOT NULL,
+
+    PRIMARY KEY (url, encrypted)
+);
+
+INSERT INTO new_discord_file (url, encrypted, id, mxc, size, width, height, mime_type, decryption_info, timestamp)
+SELECT url, encrypted, id, mxc, size, width, height, mime_type, decryption_info, timestamp FROM discord_file;
+
+DROP TABLE discord_file;
+ALTER TABLE new_discord_file RENAME TO discord_file;