Integrate `everest run --gui` and `everest results --ert_plotter`

[eilskra]

Based on user feedback, a lightweight version of the ERT GUI was wanted, rather than two separate entry points for execution and results.

"Minimum" requirements:

• A Start button to launch an Everest run
• Functionality equivalent to everest run --gui
  • Corresponding to the ERT Experiment Status-“tab”
• Functionality equivalent to everest results --ert_plotter
  • Corresponding to the ERT Create plot-“tab”

Launch command could be the equivalent of ERT's everest gui test-data/Everest ... or just a part of ert gui

[eilskra]

Screenshot of everest run --gui ..