ep: Compress EP requests (#48793)
Benchmark results on 3,000 captured requests:
| Scenario | Mean | Savings | p95 | Savings |
|:------------------|-------:|--------:|-------:|--------:|
| Uncompressed | 12,275 | — | 35,896 | — |
| zstd (no dict) | 2,784 | 77.3% | 7,193 | 80.0% |
| zstd + global dict| 2,544 | 79.3% | 6,862 | 80.9% |
| brotli (no dict) | 2,650 | 78.4% | 6,857 | 80.9% |
A trained zstd dictionary adds only 2% over plain zstd, which is not
worth added complexity.
Brotli compresses comparably but is 4 times slower.
Release Notes:
- N/A