* Add textDocument/codeAction
* Add callback for workspace/executeCommand
* Escape newlines in codeAction titles
* Return empty list in get_line_diagnostics if no buffer diagnostics
* Add stub documentation
* Validate context parameter in code_action
* Add support for edit in CodeAction responses
* Group diagnostics by line in vim.lsp.util.get_line_diagnostics()
* Advertise code action literal support