TypeScript types for Mutators
Are you submitting a bug report or a feature request?
Feature Request
What is the current behavior?
The keys are unknown on form.mutators. Unable to use IDE auto-complete to use mutators. Unable to benefit from TypeScript typing.

What is the expected behavior?
Expect the IDE to know what mutators are registered, in the sandbox example below they are printed out: insert, concat, move, etc.
Sandbox Link
Here is a very minimal example that doesn't do anything (had trouble converting the JS example to TS) but on line 9 you can type form.mutators. then Ctrl+Space and see the lack of suggestions.
https://codesandbox.io/s/awesome-dawn-tjqv0x?file=/src/index.tsx
What's your environment?
react-final-form v6.5.8
Please, this is the most requested feature for me.
I think we can use something like unistyles does with the internal theme type.
They simply have a style that we can override easily.
Docs: https://reactnativeunistyles.vercel.app/reference/theming/