Add TiDB Resource Controls

[zph]

TODO

• Setup automated testing for these changes
• Offer upstream to petoju repo
• Optionally build in lookups to see if current allocation is within limits of total predicted cluster capacity

mysql> CALIBRATE RESOURCE START_TIME '2024-07-09 19:10:21' DURATION '30m';
+--------+
| QUOTA  |
+--------+
| 160194 |
+--------+
1 row in set (0.24 sec)

That's approx NOW() - DURATION