Adding PRESUBMIT check to stop using istream, ostream and sstream.
Adding PRESUBMIT check to stop using istream, ostream and sstream.

WebRTC would like to stop using std::stringstream (in favor of
rtc::SimpleStringStream) and in order to avoid to introduce new
dependencies on it (and on other streams), this CL adds a PRESUBMIT
check.

The check will trigger anytime an #include of istream, ostream or
sstream is detected. It also ensures that new usages of types defined
in these headers are not introduced in the codebase.

Bug: webrtc:8982
Change-Id: I3e44d6a53772f25405234f10d4cf0a7209fedf99
No-Try: True
Reviewed-on: https://webrtc-review.googlesource.com/60542
Commit-Queue: Mirko Bonadei <d2c43c210eae6feef04f53bae50885e8152edcca@webrtc.org>
Reviewed-by: Tommi <74a97831ec830b6e3846c6faa50560947ae01c68@webrtc.org>
Reviewed-by: Patrik Höglund <b486136ee68458b09c92c86c39f451c87d6ef6a1@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22343}
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