ggml : support `truncate=false` for YaRN (#30206)
* ggml : support `truncate=false` for YaRN
YaRN calculates correction intervals to switch frequency interpolation
methods, but the setting to not round the boundaries of these intervals
to integers (`truncate=false`) was not supported.
Models that use `truncate=false` include gpt-oss and some PLaMo-3
models; to support them correctly, the GGML operations and CPU backend
are modified to handle calculations without rounding. The default
behavior is `truncate=true`, and existing calls not explicitly
configured will maintain their previous behavior.
* support CUDA backend
* add tests
* move RoPE helpers to internal header
* format
