src.ctf.fs: modernize read_src_fs_parameters

src.ctf.fs: modernize read_src_fs_parameters

 - Change the input parameter `params` to be bt2::ConstMapValue.
 - Changethe return type to be of a new structure type containing all
   processed parameters, rather than using output parameters and rather
   than setting the clkClsCfg inside the ctf_fs object directly.
 - Change the type of the parameters of
   ctf_fs_component_create_ctf_fs_trace and other helper functions
   accordingly.

Change-Id: I2ba5aca22f907ffcfbdd19c8d8077e17d0c47a71
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8421
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12356
Tested-by: jenkins <jenkins@lttng.org>