feat: make typings for customInput generic

[patsimm]

Describe the issue/change

We are using react-number-format together with material-ui. In our case we want to use the custumInput "TextField" but pass the prop: { size: "small" }.

When we do this we get the error:

No overload matches this call.
  Overload 1 of 2, '(props: NumberFormatProps | Readonly<NumberFormatProps>): NumberFormat', gave the following error.
    Type 'string' is not assignable to type 'number | undefined'.
  Overload 2 of 2, '(props: NumberFormatProps, context: any): NumberFormat', gave the following error.
    Type 'string' is not assignable to type 'number | undefined'.ts(2769)

The problem here is, that NumberFormatProps are typed to always extend InputAttributes. Where actually when we use a customInput there is no reason to pass InputAttributes. In that case we should be able to pass the props of the customInput.

As far as I understand this is how the actual logic works.

Add CodeSandbox link to illustrate the issue (If applicable)

https://codesandbox.io/s/beautiful-tess-eb5r6?file=/src/App.tsx

Describe the changes proposed/implemented in this PR

I updated the typings of NumberFormatProps to be generic. Now instead of always extending from InputAttributes the Props-Type of the component passed as customInput are extracted and added to the typing. Typescript is actually smart enought to this automatically.

I must say that I can not promise this does not introduce breaking changes for people that import and use the current typings. But in my opinion those generic typings are closer to how the component actually works.

Link Github issue if this PR solved an existing issue

#422

Example usage (If applicable)

See the updated typings/number_format.spec.tsx c9e0627#diff-9d8e8f0103177d8c0688a00a41889511f17c18bfa6150b4d4922aa40fc87825aR7

[s-yadav]

Sorry for looking late into this. Looks great, thanks for PR.