Investigate usage of the Embedded Trace Buffer (ETB) for robust trace exfiltration

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As documented we'll need to investigate the use of the ETB in order to robustly read the trace stream from the target from device start. This will be limited to targets that are supported by probe-rs.

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[ARM IHI 0029E]:

CoreSight systems can include the following trace sinks:

• Trace Port Interface Units (TPIUs)
• Embedded Trace Buffers (ETBs)
• Trace Memory Controllers (TMCs)

All the above seems to be parts of something called an AMBA ATB interface.