Refactor com.vaadin.flow.router.internal.AbstractNavigationStateRenderer

[mshabarov]

Describe your motivation

Code analysis highlights:

• This file has 4 bumpy roads:
  pushHistoryStateIfNeeded(bumps = 3)
  handle(bumps = 2)
  sendBeforeEnterEvent(bumps = 2)
  getPreservedChain(bumps = 2)
  A Bumpy Road is a function that contains multiple chunks of nested conditional logic inside the same function. The deeper the nesting and the more bumps, the lower the code health.

• 5 methods have high complexity.
  handle(cc = 19)
  handleTriggeredBeforeEvent(cc = 11)
  pushHistoryStateIfNeeded(cc = 10)
  getNavigationEvent(cc = 9)
  sendBeforeEnterEvent(cc = 9)

• 4 methods have complex conditionals.
  handleTriggeredBeforeEvent:738(4 complex conditional expressions)
  pushHistoryStateIfNeeded:326(3 complex conditional expressions)
  getTargetParentLayouts:308(2 complex conditional expressions)
  handleTriggeredBeforeEvent:748(2 complex conditional expressions)
  getPreservedChain:1020(2 complex conditional expressions)

• You have 1 functions that exceed the threshold.
  handle(LoC = 88 lines)

Additional context

See CodeScene analysis.