Add support for the ORBTrace mini probe

[Disasm]

This PR adds support for the ORBTrace probe. Currently only SWO-based tracing is supported.

I'm not sure if it's a good way to implement a CMSIS-DAP based device with overrides for SWO handling, but I'm open to better options :)

Tested with the orbmule target board and the following command:
cargo run --bin probe-rs --features=cli -- itm --probe 1209:3443 --chip stm32f730V8Tx swo 10000 16000000 8000000

[adamgreig]

It feels like there must be a better way to handle this, given it's 95% a normal cmsis-dap device, with just some extra support for parallel trace. Does the normal async SWO tracing work, i.e. using cmsis-dap to set baud and manchester/uart?

[Disasm]

The standard way to handle SWO is a third endpoint within CMSIS-DAP v2 interface. Unfortunately, in ORBTrace this endpoint is part of a different interface, and not supported by CMSIS-DAP. Configuration is also quite different.

[adamgreig]

Ah, I see it doesn't support SWO over CMSIS-DAP at all, that's a shame! Perhaps this is the best way then, and at least it can re-use essentially all the cmsisdap module.

By the way, the changelog update needs to be a separate file in the changelog/ directory, not a change to the actual CHANGELOG.md file.