perf(game): add player_sessions indices

[luchaos]

500ms+ to 44ms for this query:

-- EXPLAIN
SELECT
    `user_id`,
    `User`,
    `rich_presence`,
    MAX(rich_presence_updated_at) AS rich_presence_updated_at
FROM
    `player_sessions`
    INNER JOIN `UserAccounts` ON `UserAccounts`.`ID` = `user_id`
WHERE
    `game_id` = 228
    -- AND `UserAccounts`.`Permissions` >= 0
    -- AND `rich_presence` IS NOT NULL 
GROUP BY
    `user_id`
ORDER BY
    `rich_presence_updated_at` DESC;

Prepares for user-centric queries, too:

-- EXPLAIN
SELECT
    `user_id`,
    `User`,
    `rich_presence`,
    `rich_presence_updated_at`
FROM
    `player_sessions`
    INNER JOIN `UserAccounts` ON `UserAccounts`.`ID` = `user_id`
WHERE
    `user_id` = 472770
    AND `game_id` = 228
ORDER BY
    `rich_presence_updated_at` DESC;

[Jamiras]

Before (228): 47ms, 43ms, 41ms, 40ms, 46ms (average: 43ms)
After (228): 10ms, 10ms, 12ms, 10ms, 10ms (average: 10ms)

4x improvement

Before (1446): 25ms, 19ms, 20ms, 18ms, 18ms (average: 20ms)
After (1446): 10ms, 10ms, 8ms, 9ms, 7ms (average: 8ms)

2.5x improvement