Support a mix of edit and command in the code action response

[testforstephen]

The current ycmd implementation expects the code action response to have either edit or command, but not both. This is inconsistent with the LSP spec that allows both edit and command in the response. If both are supplied, the edit is applied first, then the command is executed.

ycmd/ycmd/completers/language_server/language_server_completer.py

Lines 2687 to 2700 in d3ae555

	for code_action in code_actions:
	if 'edit' in code_action:
	# TODO: Start supporting a mix of WorkspaceEdits and Commands
	# once there's a need for such
	assert 'command' not in code_action
	# This is a WorkspaceEdit literal
	fixits.append( self.CodeActionLiteralToFixIt( request_data,
	code_action ) )
	continue
	# Either a CodeAction or a Command
	assert 'command' in code_action

[bstaletic]

How could I make jdt produce such a code action in order to test the implementation? I have tried a few things, but I could not trigger that assertion.