Allow per-user tracking for patron XP gains and drystreak tools

[TastyPumPum]

This PR extends the /tools patron xp_gains and /tools patron drystreak commands so they can target a specific account instead of only showing the top 10.

For XP gains, an optional user_id argument is now accepted. When provided, the command sanitises and validates the Discord ID, filters the xp_gains query to that user, and replies with a single-line summary of their XP over the chosen interval (or a friendly “no gains found” message). Leaving user_id blank keeps the existing leaderboard behaviour unchanged.

For drystreaks, an optional user_id argument has been added alongside new helper functions for per-user checks. For monsters and openables, the command now returns a tailored message that:

• tells the user if they already have the CL item,
• explains if they have 0 KC / 0 opens (so they’re not actually dry), or
• shows their current dry streak in KC or openable count.

If no user_id is supplied, the original “top 10 driest players” leaderboard behaviour is preserved.

• I have tested all my changes thoroughly.