Resolve one TODO for command line help tests

Resolve one TODO for command line help tests

Make [PROGRAM] replacement respect the binary name passed to
CommandLineModuleManager, giving the tests full control over the help
output.

There are complications making this work nicely in the selection help
(requires some effort in propagating the information), so change the
wording there for now to avoid this tag.  Can be revisited at a later
time if/when the help writing context is more uniform for different
cases that can trigger the selection help ('gmx help ...' vs. 'help ...'
in the selection prompt).

Change-Id: I93e7dd8279d3730d38122c212174e533420859b9