Mhd/overview map refactor

[mhdostal]

This refactors the OverviewMap. Changes include:

• @State, @binding, and other property wrappers should be on the same line as the variable declaration.
• Change the OverviewMap view modifiers to use trailing closures(?), which is more readable and also appears to have fixed the indentation issues.
• Change the massive width segmented control to a nav bar trailing button with context menu to choose between map and scene.
  

#37

cc: @rolson

[dfeinzimer]

Looks good! Just the one suggestion

[zkline101]

🤙

[mhdostal]

@dfeinzimer @zkline101 Thank you!