Rethink packaging: split mlos_bench.storage out?

[bpkroth]

A small observation while thinking about #944 and #838 and #732:

With multiple component nodes in this design, not all of them need all of the different parts of MLOS installed.

• mlos_benchd_service needs mlos_bench.storage and mlos_bench which likely needs mlos_core
• mlos_viz needs mlos_bench.storage but that's all
• mlos_webui needs mlos_viz and mlos_bench.storage

We may want to extract out the mlos_bench.storage portion to its own package somehow.