Replace rtc::Optional with absl::optional in test and rtc_tools

This is a no-op change because rtc::Optional is an alias to absl::optional

This CL generated by running script with parameters 'test rtc_tools'

find $@ -type f \( -name \*.h -o -name \*.cc \) \
-exec sed -i 's|rtc::Optional|absl::optional|g' {} \+ \
-exec sed -i 's|rtc::nullopt|absl::nullopt|g' {} \+ \
-exec sed -i 's|#include "api/optional.h"|#include "absl/types/optional.h"|' {} \+

find $@ -type f -name BUILD.gn \
-exec sed -r -i 's|"(../)*api:optional"|"//third_party/abseil-cpp/absl/types:optional"|' {} \+;

git cl format

Bug: webrtc:9078
Change-Id: Ibb43c737f4c45fe300736382b0dd2d8ab32c6377
Reviewed-on: https://webrtc-review.googlesource.com/83944
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23642}

test/call_test.cc

@@ -323,7 +323,7 @@ void CallTest::CreateFrameGeneratorCapturerWithDrift(Clock* clock,
                                                      int width,
                                                      int height) {
   frame_generator_capturer_.reset(test::FrameGeneratorCapturer::Create(
-      width, height, rtc::nullopt, rtc::nullopt, framerate * speed, clock));
+      width, height, absl::nullopt, absl::nullopt, framerate * speed, clock));
   video_send_stream_->SetSource(frame_generator_capturer_.get(),
                                 DegradationPreference::MAINTAIN_FRAMERATE);
 }
@@ -332,7 +332,7 @@ void CallTest::CreateFrameGeneratorCapturer(int framerate,
                                             int width,
                                             int height) {
   frame_generator_capturer_.reset(test::FrameGeneratorCapturer::Create(
-      width, height, rtc::nullopt, rtc::nullopt, framerate, clock_));
+      width, height, absl::nullopt, absl::nullopt, framerate, clock_));
   video_send_stream_->SetSource(frame_generator_capturer_.get(),
                                 DegradationPreference::MAINTAIN_FRAMERATE);
 }