Prompted by encode/httpx#3287

starlette is currently using private imports from httpx...

https://github.com/encode/starlette/blob/c78c9aac17a4d68e0647252310044502f1b7da71/starlette/testclient.py#L500-L513

These are broken against the latest minor point release, which includes this (internal) refactoring... encode/httpx#3245

It's possible that the path of least resistance for the short term is for httpx to re-include URLTypes, tho really we need to be making sure that downstream packages are not using private imports.

Some prior discussion of this also at #2534.