Upstream zlib-ng module@2.3.2.envoy to BCR

### Module
- `zlib-ng`
- Version: 2.3.2.envoy
- BCR: ✅ exists (2.0.7 - older)
- Source: https://github.com/zlib-ng/zlib-ng

### Checklist
- [ ] PR 2.3.2 to BCR
- [ ] Update envoy to use BCR version when landed

### Notes
- Toolshed has 2.3.2, BCR has 2.0.7 (significant version gap)
- zlib-ng is a high-performance zlib replacement
