Refactoring: convert 2-branch Select...Case to If...Else block

[IvenBach]

Per @retailcoder: 'We need to be able to statically determine how to simplify that. Like #3363 but a step or two further'
https://stackoverflow.com/questions/46696941/error-16-expression-too-complex-nested-select-case

[bclothier]

Just to point out some test cases that may be helpful.

This generally shouldn't be a problem:

Select Case Foo
  Case 1
    DoThis
 Case 2
   DoThat
 Case 3
   Select Case Bar
      Case "a"
        Durr
      Case "b"
        Doh
      Case Else
        Daww
    End Select
End Select

OTOH, this definitely smells:

Select Case Foo
  Case 1
    Select Case Bar
      Case "a"
        DoThat
      Case "b"
        DoThis
      Case Else
        Daww
   End Select
 Case 2
   Select Case Bar
      Case "a"
        DoThis
      Case "b"
        DoThat
      Case Else
        Daww
   End Select
 Case 3
   Select Case Bar
      Case "a"
        Durr
      Case "b"
        Doh
      Case Else
        Daww
    End Select
  Case Else
     GiveUp
End Select

Note that the 2nd condition need not be repeated for all cases; having the condition duplicated in 2 branch should be sufficient to trigger the inspection as it violates the DRY rule.

But this might be actually OK, though it can be argued that there are other quality problems with the code:

Select Case Foo
  Case 1
    Select Case Bar
      Case "a"
        DoThat
      Case "b"
        DoThis
      Case Else
        Daww
   End Select
 Case 2
   Select Case NotBar
      Case 0
        DoThis
      Case 1
        DoThat
      Case Else
        Daww
   End Select
 Case 3
   Select Case SomeThingElse
      Case "z"
        Doh
      Case "y"
        Durr
      Case Else
        Daww
    End Select
End Select

The example doesn't technically repeat anything, though the logic is likely unnecessarily hard to follow but I think that's a different scope for a different inspection (maybe "TooMuchConditions" inspection?).