Add ability to use distributed conduits

[ktras]

• Add a distributed conduit to Github CI for testing purposes (probably udp-conduit)
• Add argument to install script to pick the conduit (have default be smp conduit)
• Decide long term plans, so design doesn't require running install script multiple times for use of different conduit setups and therefore installing gasnet multiple times (which is not required since one build of gasnet has all of the conduit options available for a given build mode)

Note: in install.sh, this line pkg="gasnet-smp-seq" is the line that sets the conduit

[ktras]

Ability to use distributed conduit, whether in the CI or not as is in the task list above, is the most important aspect of this issue.