Re: [RFC PATCH] fetch: stop emitting duplicate transfer.credentialsInUrl=warn warnings

> Improve on 6dcbdc0d661 (remote: create fetch.credentialsInUrl config,
> 2022-06-06) by fixing the cases where we emit duplicate warnings,
> which were:
>
>  * In the same process, as we'd get the same "struct remote *"
>    again. We could probably save ourselves more work in those scenarios,
>    but adding a flag to the "struct remote" indicating that we've validated
>    the URLs will fix those issues.
>
>  * When we invoke e.g. "git-remote-https" (aka. "git-remote-curl")
>    from "git fetch". For those cases let's pass down the equivalent of a
>    "-c transfer.credentialsInUrl=allow", since we know that we've already
>    inspected our remotes in the parent process.
>
>    See 7390f05a3c6 (fetch: after refetch, encourage auto gc repacking,
>    2022-03-28) for prior use of git_config_push_parameter() for this
>    purpose, i.e. to push config parameters before invoking a
>    sub-process.