LSP code actions

See Language Server Specification (Code Action Request) for details.

List of currently available code actions:

Code Action	Kind
Import Class	quickfix.import_class
Add Missing Return Types	quickfix.complete_constructor
Add Missing Assignments	quickfix.add_missing_properties
Implement Contracts	quickfix.implement_contracts
Fix Namespace or Class Name	quickfix.fix_namespace_class_name
Class New	quickfix.create_class
Class New	quickfix.create_unresolvable_class
Generate Method	quickfix.generate_method
Extract Method	quickfix.extract_method
Extract Expression	quickfix.extract_expression
Extract Constant	quickfix.extract_constant
Generate Accessors	quickfix.generate_accessors