Is your feature request related to a problem? Please describe.
Both paramiko and globus dependencies are rarely used, and bring in weight to the base parsl install.
At least paramiko has caused problems even when not being used due to occasional incorrect binary installs of its unix .so file.

These dependencies don't need to be installed most of the time.

Describe the solution you'd like
The components which use these - the globus staging provider, and the ssh channel - should become install optoins in the same way as the various other components are optional.