Feature request: Public API for `HTTP.RetryRequest.isrecoverable(::Exception)`

[DilumAluthge]

@ericphanson and I are using HTTP.RetryRequest.isrecoverable(::Exception) in GitHub.jl, as part of the new rate-limiting handling that Eric has added.

IIUC, currently HTTP.RetryRequest.isrecoverable(::Exception) is not public API. (At least, I can't find anything when searching for isrecoverable in the HTTP.jl manual.)

Would it be possible to either make HTTP.RetryRequest.isrecoverable(::Exception) public, or add a different public API that gives the same functionality? That way, GitHub.jl won't have to use HTTP.jl internals.

[DilumAluthge]

@quinnj Any thoughts?