Introduce HttpMessageConverter#canWriteRepeatedly

[bclozel]

The AbstractHttpMessageConverter#supportsRepeatableWrites contract is a protected method that message converters can override. This method tells whether the current converter can write several times the payload given as a parameter. This is mainly useful on the client side, where we need to know if we can send the HTTP message again, after receiving an HTTP redirect status.

Because this method is protected, this limits our ability to call it from a different package; this is needed for #33263.

With this issue, we should promote this method to the main HttpMessageConverter and deprecate the former.

[pythaac]

Hi @bclozel !
Given that #36253 is already in progress, I just wanted to verify if this one is available for contribution before I start🙂

[bclozel]

Hi @pythaac it's also mostly done already. All the related issues assigned to me are in progress already.