[Introspection] Expose supported nominal/data bitrate capabilities for detected CAN channels

[mickeyl]

Hi maintainers,

I’m integrating python-can into a UI tool that uses can.interface.detect_available_configs() to list adapters/channels.

Current situation:

• detect_available_configs() gives interface/channel candidates, which is great.
• But there is no standardized way to discover supported nominal bitrate(s) and CAN-FD data bitrate(s) per detected channel.
• As a result, UIs have to hardcode bitrate presets, which can be wrong for specific hardware/drivers.

Feature request:

• Add optional capability fields to auto-detected configs (or a related capability API), e.g.:
  • supported_bitrates: list[int] | None
  • supported_data_bitrates: list[int] | None (for FD-capable channels)
  • supports_fd: bool | None

Example output shape:

{
  "interface": "socketcan",
  "channel": "can0",
  "supports_fd": True,
  "supported_bitrates": [125000, 250000, 500000, 1000000],
  "supported_data_bitrates": [1000000, 2000000, 4000000]
}

Would that make sense?