refactor(prompts): Normalize playground instance messages (#6218)

* refactor(prompts): Normalize playground instance messages

* Update use-zustand package to improve performance

* Convert TemplateEditor, VariableEditor, and PlaygroundTool (editor) to uncontrolled components

Workaround for https://github.com/uiwjs/react-codemirror/issues/694

* Clean up variable names and semantics

* Mark instance as dirty when updating message