sink.ctf.fs: write boolean field classes and fields

sink.ctf.fs: write boolean field classes and fields

This patch makes a `sink.ctf.fs` component handle boolean field classes
and fields. Because CTF 1.8 has no boolean field class type, it makes a
best effort and translates it to an 8-bit unsigned integer field class.
A boolean field is written as an 8-bit unsigned integer field having the
value 0 (false) or 1 (true).

When a `src.ctf.fs` component reads a trace generated by `sink.ctf.fs`
where the input trace IR contained boolean field classes, the 8-bit
unsigned integer field classes will stay integer field classes; the
source component has no way to determine if the metadata describes a
boolean field class or a genuine integer field class. However, the CTF
1.8 to CTF 1.8 scenario will always be unambiguous because a
`src.ctf.fs` component never creates boolean field classes.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I6be5967c2312bdb0e67be7db14ab663912872403
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1895
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>