Don't wrap fish_indent at all if the version in $PATH matches
$FISH_VERSION.
When we do wrap it, resolve the path once, and use that via alias
machinery instead of doing an eval each time.
In both cases, `type fish_indent` can tell us what it's actually going
to do now.
clarity aside, it's faster if we only eval the one time.
eval is not only evil, but slow.
> for h in $history[1..100]; echo $h | fish_indent --no-indent; end
before: CMD_DURATION = 1005
if fish_indent is kosher in PATH: 549
if not, using alias: 687