## Summary
Extend `BreakBinaryOperations` to accept a structured YAML configuration
with per-operator break rules and minimum chain length gating via
`PerOperator`.
- **Per-operator rules**: specify break style (`Never`, `OnePerLine`,
`RespectPrecedence`) for specific operator groups
- **Minimum chain length**: only trigger breaking when a chain has N or
more operators
- **Fully backward-compatible**: the simple scalar form
(`BreakBinaryOperations: OnePerLine`) behaves identically to the current
enum value
RFC discussion:
https://discourse.llvm.org/t/rfc-per-operator-granularity-for-breakbinaryoperations/89800
### New YAML syntax
```yaml
BreakBinaryOperations:
Default: Never
PerOperator:
- Operators: ['&&', '||']
Style: OnePerLine
MinChainLength: 3
- Operators: ['|']
Style: OnePerLine
```
### Motivation
`BreakBinaryOperations` operates at the level of all binary operators
simultaneously. Enabling `OnePerLine` for `&&`/`||` condition chains
also forces it on `+`, `|`, and other operators, which may not be
desired. The only workaround today is `// clang-format off`.
## Test plan
- [x] All existing `BreakBinaryOperations` unit tests updated and
passing
- [x] New tests for per-operator rules (`&&`/`||` OnePerLine + default
Never)
- [x] New tests for multiple operator groups (`&&`/`||` + `|`)
- [x] New tests for `MinChainLength` gating (chain of 2 vs 3+)
- [x] Config parse tests for structured YAML form
- [x] RST documentation auto-generated via `dump_format_style.py`
- [x] Release notes updated
62e55b410c