Ensure C compatibility for guest tracing

[dblnz]

Description

We want Hyperlight guest tracing to be compatible with C guests.
We haven't tried it, but using a C guest should at least allow the hyperlight guest framework traces to be reported to the host.

Rationale

All type of Hyperlight guests shall have support for guest tracing.

How

We need tests to ensure this compatibility.
Furthermore, to allow a guest to add custom traces in its code, we need to provide some macros/APIs that do that for the C guests. Or find a way to exercise the tracing subscriber's APIs.