This allows instruments to record a diagnostic and have it land as an
object in a GListModel of diagnostics available to the API consumer.
Such items may be used by recording UI to display issues with the recording
to the user.
We might have the file data from the peer and can specify the data in the
capture writer directly.
It may be useful to allow compressing these too, but we can deal with that
at a later time.
The goal here is to have a fairly small exposed API surface for profiling
similar to libsysprof-analyze where implementation details are hidden.
SysprofProfiler - Where you setup your recording
SysprofInstrument - What you add to a profiler to extract data
SysprofRecording - Represents an active recording w/ instruments
