2-way Binding Support

[StevenLambion]

This PR adds a convenient API to provide better support of SwiftUI views that use Binding<_> for their arguments. It combines a state value with a setter-based action that is expected to update it.

Work Performed

• Added StateBinder
• Added new API to Connectable and ParameterizedConnectable to include StateBinder when mapping the application state to a view.

[codecov-io]

Codecov Report

Merging #22 into master will not change coverage.
The diff coverage is 100%.

@@         Coverage Diff          @@
##           master   #22   +/-   ##
====================================
  Coverage      60%   60%           
====================================
  Files          15    15           
  Lines         410   410           
====================================
  Hits          246   246           
  Misses        164   164

Impacted Files	Coverage Δ
Sources/SwiftDux/State/OrderedState.swift	81.45% <100%> (ø)	⬆️

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