Closes #575
Closes #583

Description

The code was maybe a bit cluttered/hard to follow. This attempts to break the functionality up a bit better (moves caching into its own class).

Few functionality changes also:

• Hoists currently selected binary to top of list when choosing
• cadence.changeCadenceVersion command was a bit of a misnomer which came from the initial vision of this feature (but has deviated since). This was changed to cadence.changeFlowCliBinary
• Also fixes a bug where the CLI version selection would break if an invalid flow command was configured at startup.
• Fixes "bug" when not in workspace folder

For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels