Cleanup: debug-info: remove include indirection

Cleanup: debug-info: remove include indirection

- Include `babeltrace.h` to use the `bt_field_class` definition directly
instead of relying on `trace-ir-mapping.h`'s inclusion.

- Include `debug-info.h` to use `IP_FIELD_NAME` and `VPID_FIELD_NAME`
defines.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I16d9614f6bdb405e02c2d9f4ee18e02013d1c919
Reviewed-on: https://review.lttng.org/c/babeltrace/+/3614
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>