* Automatically update local variable debug info

When manipulating the local variables collection on a method body, automatically update the debug info for all affected local variables.

When removing a local variable, also remove the debug info for that local variable from the scopes.

When removing or inserting update the indeces of local variable debug infos which are afected by the action. Note the local variable debug info either holds just a backpointer to the local variable in which case it doesn't store the index at all (and thus nothing to do), or it stores the index explicitly in which case it needs to be updated.

Added tests for both insert and remove cases.

* Add internal properties on `VariableOffset` to make it easier to manipulate it.

Reworked the `UpdateVariableIndeces` to only loop over variables once and also to handle removal of resolved variable debug infos.

* Simplify the code a little and add comments

* PR feedback