Proposal: Add Property lambda Expressions

Based on #397 , this syntax can be generalized to be used outside Xml literals, by wrapping a code block in `Get` `End Get` like This:
```VB.NET
Dim X = Get
' Some code
Return Some Value
End Get
```

This is a ReadOnly Property lambda Expression, which can be implemented as real property (which will need many params to pass the local variables, and I think this is not appropriate although VB properties can have params), or It can be implemented directly as a full function that receives the local vars.
It also can be implemented to lambda function:
```VB.NET
Dim X = (Function( )
' Some code
Return Some Value
End Function) ( )
```

It may seems that the second syntax (lambda function) is not too long than the first one (lambda property), but I always feel that calling lambda expression inline is confusing and less readable.

Another example:
```VB.NET
Dim Count = ReadCount()
Dim Msg = Get
Select Case Count
Case 1
Return "One Item"
Case 2
Return "Two Items"
Case Else
Return "Many Items"
End Select
End Get
```

Not: this proposal doesn't cancel #397. I still want to get rid of `(Function() End Function) ( )` and `Get ...End Get` inside xml, and interpolated strings. Inside any literal that has a notation to substitution, there is no need to wrap code in any other container, unless there is a need to do further calculation on the returned value (like summation).
VB was always smart, and should continue this way.