please expose the formDataToStream for public use

[fancy45daddy]

Is your feature request related to a problem? Please describe.

• I need to write my own adapter, i need to use formDataToStream to deal with multipart/form-data, but formDataToStream is not available in name space axios, I want to axios.formDataToStream to be available

Describe the solution you'd like

add

import formDataToStream from './helpers/formDataToStream.js';
axios.formDataToStream = formDataToStream;

to axios/lib/axios.js

Describe alternatives you've considered

No response

Additional context/Screenshots

No response