LSP: Add textDocument/codeAction support (#11607)

* 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

runtime/lua/vim/lsp/protocol.lua

@@ -620,6 +620,15 @@ function protocol.make_client_capabilities()
         -- Send textDocument/didSave after saving (BufWritePost)
         didSave = true;
       };
+      codeAction = {
+        dynamicRegistration = false;
+
+        codeActionLiteralSupport = {
+          codeActionKind = {
+            valueSet = {};
+          };
+        };
+      };
       completion = {
         dynamicRegistration = false;
         completionItem = {