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/postgres/000026_create_preferences.up.sql

@@ -0,0 +1,53 @@
+CREATE TABLE IF NOT EXISTS preferences (
+    userid varchar(26) NOT NULL,
+    category varchar(32) NOT NULL,
+    name varchar(32) NOT NULL,
+    value varchar(2000),
+    PRIMARY KEY (userid, category, name)
+);
+
+CREATE INDEX IF NOT EXISTS idx_preferences_category ON preferences(category);
+CREATE INDEX IF NOT EXISTS idx_preferences_name ON preferences(name);
+
+DO $$
+<<modify_column_type_if_type_is_different>>
+DECLARE
+    type_exists boolean := false;
+    col_exists boolean := false;
+BEGIN
+    SELECT count(*) != 0 INTO col_exists
+    FROM information_schema.columns
+    WHERE table_name = 'preferences'
+    AND table_schema = current_schema()
+    AND column_name = 'value';
+
+    SELECT count(*) != 0 INTO type_exists
+    FROM information_schema.columns
+    WHERE table_name = 'preferences'
+    AND table_schema = current_schema()
+    AND column_name = 'value'
+    AND data_type = 'character varying'
+    AND character_maximum_length = 2000;
+
+    IF col_exists AND NOT type_exists THEN
+        ALTER TABLE preferences ALTER COLUMN value TYPE varchar(2000);
+    END IF;
+END modify_column_type_if_type_is_different $$;
+
+DO $$
+<<rename_solarized_theme>>
+DECLARE
+    preference record;
+BEGIN
+    FOR preference IN
+        SELECT * FROM preferences WHERE category = 'theme' AND value LIKE '%solarized_%'
+    LOOP
+        UPDATE preferences
+            SET value = replace(preference.value, 'solarized_', 'solarized-')
+        WHERE userid = preference.userid
+        AND category = preference.category
+        AND name = preference.name;
+    END LOOP;
+END rename_solarized_theme $$;
+
+DROP INDEX IF EXISTS idx_preferences_user_id;