feat: Added ability to provide patching function to setStatus method

[dan-irf]

Problem

When setting status, sometimes user needs to update the existing value. When used inside a useCallback hook for instance, it introduces an unnecessary variable to the dependency list.

Solution

setStatus now acepts a patching function

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[dan-irf]

@quantizor @johnrom @jaredpalmer just wanted to ask you for PR review explicitly

[johnrom]

I'm not sure what the purpose of this change is. Are you creating a new status based on the last status? It's not really clear by default where this status comes from (render or state), so I would expect Formik (if it is being brought back from the dead) to move in a direction where the source of this value can be determined explicitly, either within a render using useFormikContext().status, or the absolute current value which may be "ahead" of the render, using a getState()-like API, similar to redux.

const { setStatus, getState, status } = useFormikContext();

useEffect(() => { setStatus(status === "value in current render" ? "a" : "b"); }, [setStatus, status]);
useEffect(() => { setStatus(getState().status === "absolutely current value" ? "a" : "b"); }, [setStatus, getState]);

You can see what that API could look like here: #3231 (the file doesn't load initially, so check Formik.tsx -> useFormik -> useFormikSubscription()).