Is your feature request related to a problem? Please describe.
We currently have three different ways to launch sasview when running from source. Now that sasview is pip-installable, we should prioritize this usage over any other.

• run.py:
  • Originally created in order to launch from source, this launches cli.py after adding parallel sibling repos to the python path
  • Pros: Easy to use, does not require a pip install of sasview and sibling repos
  • Cons: Breaks the pip install paradigm, breaks some IDE enviroments
• cli.py:
  • The entry point for launching the SasView app, enabling scripting as part of the launch and within the SasView app
  • Pros: Command line interface allows script execution
  • Cons: Not in the base sasview directory
• sasview:
  • The pip-installed version of sasview, which can be either a wheel downloaded from pypi, or a local repo mapped to the python path.
  • Pros: Always uses the developer environment, allows for easy integration of sibling project changes
  • Cons: Slightly more initial setup (pip install every sibling repo)

Describe the solution you'd like
We should prioritize the usage of sasview when running from source. This gives developers more flexibility in how they setup their local system, while still enabling local testing of changes made in sibling repos.