ipptransform: Add a way ("--list-defaults" option?) to report the default values used for unspecified options

Is your feature request related to a problem? Please describe.
A user has no way of knowing what default values ipptransform will use unless they use it and inspect the output. One would assume, for instance, that if the input document uses US Letter, the output will also use US Letter, but that isn't currently the case, as is described in Issue #102. So having a way for ipptransform to report its defaults would be helpful.

Describe the solution you'd like
Add a new option like "--list-defaults" (you pick the name - what its called isn't important). or perhaps extend an existing option like "--help", that will output the default values used for all the named options supplied with the "-o" option, and also the "-r" (Resolution), "-s" (backside coordinate system), and "-t" (output color space and bit depth). One would use it like so:

$ ipptransform --list-defaults

If these can vary based on output format, then being able to specify an output format as well could be useful. Something like:

$ ipptransform --list-defaults -m image/pwg-raster

Describe alternatives you've considered
The only alternative is to just try it and see if you can tell what ipptransform is doing.

Additional context
n/a