Remove Babeltrace 1 files and reorganize the tree

Remove Babeltrace 1 files and reorganize the tree

This is one of the patches that you won't easily forget.

This patch removes the remaining legacy files, moving them if we still
need them, and reorganizes the tree as such:

* formats/ is removed
* formats/ctf/ir/ is moved to lib/ctf-ir/
* formats/ctf/writer/ is moved to lib/ctf-writer/
* types/ is removed

Because some of the CTF IR and CTF writer objects are so coupled, both
components are in libbabeltrace now. The build system creates a symbolic
link from libbabeltrace-ctf (where CTF writer used to reside) to
libbabeltrace, so that `-lbabeltrace-ctf` still works for the current
users of CTF writer.

converter/babeltrace-log.c still exists, but it's not build as of this
patch because it uses the legacy API. We need to change this to use CTF
writer and add it to the Makefile again.

Some debug info files are gone because they also use the legacy API.
They are updated anyway as part of the upcoming debug info component
class.

The Python bindings are not covered by this patch: a subsequent patch
should fix them at once.

Some tests which used the legacy API are removed.

The legacy include files are removed, except for
include/babeltrace/ctf/event.h which could be included by CTF writer
users. The file simply includes all the CTF writer header files now.

The functions to serialize integer and floating point number fields
are moved to lib/ctf-writer/serialize.c where a light
`struct bt_ctf_stream_pos` exists along with a few helper functions
for this renamed legacy object. The serialization functions use BT 2
objects now so that the dependency on the legacy API can be dropped.

The serialization functions accept a native byte order parameter now.
When a field type has a "native" byte order, the real (passed) native
byte order must be used. This ensures that:

* CTF IR objects do not need to propagate the trace's native byte order
  to all the contained field types.

* Two references to the same field type which are part of two different
  trace objects can have a native byte order without causing byte order
  overwriting bugs.

The CTF IR code is simplified with this change. Also the
bt_ctf_trace_set_byte_order() function refuses the
BT_CTF_BYTE_ORDER_NATIVE byte order.

I also added internal inline functions to quickly access the parent
of some CTF IR object without getting a new reference:

* bt_ctf_event_borrow_event_class()
* bt_ctf_event_class_borrow_stream_class()
* bt_ctf_stream_class_borrow_trace()

Since the CTF parser test in formats/ctf/metadata/ was a legacy tool,
it's removed in this patch. It's not used anymore by test_ctf_writer
(only the converter runs to validate the generated trace).

Leaks are fixed in test_ctf_ir_ref and test_trace_listener.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>