lib: move trace class's name, UUID, and environment props to trace API

lib: move trace class's name, UUID, and environment props to trace API

This patch moves the name, UUID, and environment properties of the trace
class API to the trace API. The rationale behind this is that those
properties fundamentally belong to the instance of a trace class, not to
the class itself, as many traces with different names, UUIDs, and
environments can be created from a single trace class.

With this patch, a trace class becomes a simple container of stream
classes. Its name property is removed because it's not needed currently.

Specific, non-trivial changes:

`ctf` plugin:
    ctf_trace_class_translate() does not translate the UUID and
    environment anymore. Those properties are still part of a CTF IR
    trace class however. Instead, the new
    ctf_trace_class_configure_ir_trace() function can configure a trace
    IR trace object from the properties of a CTF IR trace class object.

    Both `src.ctf.fs` and `src.ctf.lttng-live` use
    ctf_trace_class_configure_ir_trace().

`sink.ctf.fs`:
    The private CTF IR trace class object is renamed to
    `fs_sink_ctf_trace` as it represents a single trace anyway.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: Idaffd34c3ce28682b2c490588fccc963fcb1f3fa
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1640
Tested-by: jenkins <jenkins@lttng.org>