Add move method to parent class refactor

[vinistock]

Add a new code action to move the selected method implementation to the parent class. For example:

# BEFORE
class Parent
end

class Child < Parent
  def foo
  end
end

# AFTER
class Parent
  def foo
  end
end

class Child < Parent
end

Here's an example PR adding a refactor end to end #2372.

[andyw8]

I'd suggest calling this "Pull Up Method" to match the naming in https://refactoring.com/catalog/