helper/command: pass command arguments also as Jim_Obj

helper/command: pass command arguments also as Jim_Obj

Some OpenOCD command gets fragment of TCL scripts as command-line
argument, fragments that will be kept and executed later on.
E.g. the command 'configure' gets the body of an OpenOCD event:
	$TARGET configure -event halted {TCL code}

These commands store the argument as a Jim_Obj and pass it to the
jimtcl interpreter when the TCL fragment has to be executed.
Using Jim_Obj as storage is relevant to let the jimtcl interpreter
to recover extra info of the TCL fragment, like the file-name and
the line-number that contain the fragment, that will be printed
out in case of run-time errors.

While converting the commands to COMMAND_HANDLER, we should avoid
storing the argument as C strings otherwise we will loose precious
info in case of run-time errors making challenging the debugging
of such TCL fragments.

Extend the struct command_invocation to contain the array that
points to the Jim_Obj of the command arguments.
This will be used while converting commands to COMMAND_HANDLER.

Change-Id: If37c5f20e9a71349f77ba1571baf1e6778e28aa5
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8057
Tested-by: jenkins