lib: commonize some precondition assertion macros

lib: commonize some precondition assertion macros

1. Rename `assert-cond.h` to `assert-cond-base.h`.

2. Move common specialized pre/postcondition macros from
   `assert-cond-base.h` to `assert-cond.h`.

   Now `assert-cond-base.h` only contains the very basic
   pre/postcondition assertion macros.

3. Move common specialized macros from various internal header files to
   `assert-cond.h`.

4. Add new common specialized macros to `assert-cond.h`, mostly "non
   null" precondition assertion macros.

The goal of this patch is to make it easy to change code for many sites
at the same time when those sites use the same macro.

This patch introduces the common precondition assertion macros, but
does not use them in source files (future patch).

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I2456e459bab9d942e4e11953b4afc5a6f4d30620
Reviewed-on: https://review.lttng.org/c/babeltrace/+/3433