Define an object for collecting DSLX interpreter events.

[meheff]

The newly defined DslxInterpreterEvents gathers assert and trace messages from the DSLX interpreter replacing the previous trace hook mechanism. It stores information in the same proto as the IR interpreter does which enables easier comparison of behavior between the interpreters and the sharing of tools. Also augment the proto with additional information like source information.

Also add a utility dump_call_trace which reads an events proto and prints a structured trace of the calls.

[meheff]

Any progress on this? Thanks.

[proppy]

@richmckeever: ping for review ? adding @cdleary too.

[ericastor]

@meheff Please rebase this when you can; we can't pull it in for final review until conflicts are resolved.

[meheff]

Rebased to head... and changed my notifications for the XLS repo to my personal email account as I kept missing responses on my PRs (my work email might as well be /dev/null).

[mikex-oss]

@meheff sorry, I missed this. Can you please add Apache license headers? The migration is failing with:

error: Error validating 'verify_match 'Licensed under the Apache License, Version 2.0'': xls/dev_tools/dump_call_trace.cc - Expected string was not present.

Error validating 'verify_match 'Licensed under the Apache License, Version 2.0'': xls/dev_tools/dump_call_trace_test.py - Expected string was not present.

[meheff]

Added licenses.

[proppy]

@meheff did you get a change to look at @mikex-oss comments?

[proppy]

this also need to be rebased.