boards: bsim: fix bug with single settings file for few bsim devices

Reapply the part of 4b5cd92312
that added new functionality/fixed the actual issues described
in the original commit message withtout the further cleanup.

There was also some cross-commit content from
2b91ebe16e
as part of the cleanup in test_friendship.c which is also included.
+ added cleanup also to test_provision.c on request from Aleksandr.

Original commit msg:
-----------
Multiple bsim devices cannot store individual settings
with the existing settings backend for bsim.

Signed-off-by: Aleksandr Khromykh <aleksandr.khromykh@nordicsemi.no>
-----------

Signed-off-by: Alberto Escolar Piedras <alpi@oticon.com>

boards/posix/nrf52_bsim/argparse.c

@@ -226,5 +226,15 @@ void nrfbsim_cleanup_args(void)
 	bs_cleanup_dynargs(&args_struct);
 }
 
+char *get_simid(void)
+{
+	return arg.s_id;
+}
+
+unsigned int get_device_nbr(void)
+{
+	return arg.global_device_nbr;
+}
+
 NATIVE_TASK(nrfbsim_register_args, PRE_BOOT_1, 0);
 NATIVE_TASK(nrfbsim_cleanup_args, ON_EXIT, 10);

boards/posix/nrf52_bsim/argparse.h

@@ -26,6 +26,8 @@ struct NRF_bsim_args_t {
 
 struct NRF_bsim_args_t *nrfbsim_argsparse(int argc, char *argv[]);
 void bs_add_extra_dynargs(bs_args_struct_t *args_struct_toadd);
+char *get_simid(void);
+unsigned int get_device_nbr(void);
 
 #ifdef __cplusplus
 }