TBR: cmdline: Allow passing a list of LookPathPrefixes which the command will use to look for subcommands.
TBR: cmdline: Allow passing a list of LookPathPrefixes which the command will
use to look for subcommands.

In a later CL, I'm planning on renaming the "v23-" subcommands to
"jiri-".  This CL is needed so that the v23 tool can find the new jiri-
subcommands.

MultiPart: 1/2
Change-Id: Ie286f7a288abc0e1ed3f0303e1c7c45cd2d47688

vanadium/go.lib