Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/db/migrations/mysql/000006_create_emojis.up.sql

@@ -0,0 +1,73 @@
+CREATE TABLE IF NOT EXISTS Emoji (
+    Id varchar(26) NOT NULL,
+    CreateAt bigint(20) DEFAULT NULL,
+    UpdateAt bigint(20) DEFAULT NULL,
+    DeleteAt bigint(20) DEFAULT NULL,
+    CreatorId varchar(26) DEFAULT NULL,
+    Name varchar(64) DEFAULT NULL,
+    PRIMARY KEY (Id),
+    UNIQUE KEY (Name, DeleteAt),
+    KEY idx_emoji_update_at (UpdateAt),
+    KEY idx_emoji_create_at (CreateAt),
+    KEY idx_emoji_delete_at (DeleteAt)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.statistics
+        WHERE table_name = 'Emoji'
+        AND table_schema = DATABASE()
+        AND index_name = 'idx_emoji_create_at'
+    ) > 0,
+    'SELECT 1',
+    'CREATE INDEX ON Emoji(CreateAt);'
+));
+
+PREPARE createIndexIfNotExists FROM @preparedStatement;
+EXECUTE createIndexIfNotExists;
+DEALLOCATE PREPARE createIndexIfNotExists;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.statistics
+        WHERE table_name = 'Emoji'
+        AND table_schema = DATABASE()
+        AND index_name = 'idx_emoji_delete_at'
+    ) > 0,
+    'SELECT 1',
+    'CREATE INDEX ON Emoji(DeleteAt);'
+));
+
+PREPARE createIndexIfNotExists FROM @preparedStatement;
+EXECUTE createIndexIfNotExists;
+DEALLOCATE PREPARE createIndexIfNotExists;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.statistics
+        WHERE table_name = 'Emoji'
+        AND table_schema = DATABASE()
+        AND index_name = 'idx_emoji_update_at'
+    ) > 0,
+    'SELECT 1',
+    'CREATE INDEX ON Emoji(UpdateAt);'
+));
+
+PREPARE createIndexIfNotExists FROM @preparedStatement;
+EXECUTE createIndexIfNotExists;
+DEALLOCATE PREPARE createIndexIfNotExists;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.STATISTICS
+        WHERE table_name = 'Emoji'
+        AND table_schema = DATABASE()
+        AND index_name = 'idx_emoji_name'
+    ) > 0,
+    'DROP INDEX idx_emoji_name ON Emoji;',
+    'SELECT 1'
+));
+
+PREPARE removeIndexIfExists FROM @preparedStatement;
+EXECUTE removeIndexIfExists;
+DEALLOCATE PREPARE removeIndexIfExists;