[trace][intel-pt] Create basic SB API

This adds a basic SB API for creating and stopping traces.
Note: This doesn't add any APIs for inspecting individual instructions. That'd be a more complicated change and it might be better to enhande the dump functionality to output the data in binary format. I'll leave that for a later diff.

This also enhances the existing tests so that they test the same flow using both the command interface and the SB API.

I also did some cleanup of legacy code.

Differential Revision: https://reviews.llvm.org/D103500