feat: add MMR update benchmarking script and bulk MMR update

[ershisan99]

update mmr as a single query instead of a Promise.all() creating multiple connections to the db.

don't expect anything notable, but it's a good first step towards a more global goal

=== Results ===

┌───┬───────────────────────────┬───────────────────┬──────┬──────────┬─────────────┐
│   │ Test                      │ Avg Duration (ms) │ Ops  │ Ops/sec  │ Memory (KB) │
├───┼───────────────────────────┼───────────────────┼──────┼──────────┼─────────────┤
│ 0 │ 10 players - individual   │ 416.16            │ 10   │ 24.03    │ 174.20      │
│ 1 │ 10 players - bulk         │ 42.17             │ 10   │ 237.15   │ 41.52       │
│ 2 │ 50 players - individual   │ 2129.61           │ 50   │ 23.48    │ 681.05      │
│ 3 │ 50 players - bulk         │ 44.60             │ 50   │ 1121.07  │ 70.51       │
│ 4 │ 100 players - individual  │ 4178.78           │ 100  │ 23.93    │ 1267.43     │
│ 5 │ 100 players - bulk        │ 42.98             │ 100  │ 2326.53  │ 131.76      │
│ 6 │ 500 players - individual  │ 20977.20          │ 500  │ 23.84    │ 6201.65     │
│ 7 │ 500 players - bulk        │ 76.07             │ 500  │ 6573.23  │ 576.18      │
│ 8 │ 1000 players - individual │ 42124.77          │ 1000 │ 23.74    │ 12412.24    │
│ 9 │ 1000 players - bulk       │ 86.04             │ 1000 │ 11622.61 │ 1083.53     │
└───┴───────────────────────────┴───────────────────┴──────┴──────────┴─────────────┘

=== Performance Comparison ===

10 players:
  Bulk is 9.87x faster
  Time saved: 373.99ms
  Memory diff: -132.67KB

50 players:
  Bulk is 47.75x faster
  Time saved: 2085.01ms
  Memory diff: -610.54KB

100 players:
  Bulk is 97.22x faster
  Time saved: 4135.79ms
  Memory diff: -1135.67KB

500 players:
  Bulk is 275.78x faster
  Time saved: 20901.14ms
  Memory diff: -5625.47KB

1000 players:
  Bulk is 489.60x faster
  Time saved: 42038.73ms
  Memory diff: -11328.71KB

[robotzurg]

Looks great!