Replace rtc::Optional with absl::optional

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

This CL generated by running script from modules with parameters
'pacing video_coding congestion_controller remote_bitrate_estimator':

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: I8ea501d7f1ee36e8d8cd3ed37e6b763c7fe29118
Reviewed-on: https://webrtc-review.googlesource.com/83900
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23640}
diff --git a/modules/video_coding/BUILD.gn b/modules/video_coding/BUILD.gn
index 18baa68..90ab60a 100644
--- a/modules/video_coding/BUILD.gn
+++ b/modules/video_coding/BUILD.gn
@@ -17,7 +17,6 @@
   deps = [
     ":video_codec_interface",
     "../../:webrtc_common",
-    "../../api:optional",
     "../../api/video:video_frame_i420",
     "../../common_video:common_video",
     "../../modules:module_api",
@@ -28,6 +27,7 @@
     "../../rtc_base/experiments:alr_experiment",
     "../../system_wrappers:field_trial_api",
     "../../system_wrappers:system_wrappers",
+    "//third_party/abseil-cpp/absl/types:optional",
   ]
 
   if (!build_with_chromium && is_clang) {
@@ -165,7 +165,6 @@
     "../..:webrtc_common",
     "../../:typedefs",
     "../../api:fec_controller_api",
-    "../../api:optional",
     "../../api/video:encoded_frame",
     "../../api/video:video_frame",
     "../../api/video:video_frame_i420",
@@ -185,6 +184,7 @@
     "../../system_wrappers:metrics_api",
     "../rtp_rtcp:rtp_rtcp_format",
     "../utility:utility",
+    "//third_party/abseil-cpp/absl/types:optional",
   ]
 }
 
@@ -258,7 +258,6 @@
     "..:module_api",
     "../..:webrtc_common",
     "../../:typedefs",
-    "../../api:optional",
     "../../api/video_codecs:video_codecs_api",
     "../../common_video",
     "../../modules/rtp_rtcp",
@@ -270,6 +269,7 @@
     "../../rtc_base/experiments:quality_scaling_experiment",
     "../../system_wrappers",
     "../rtp_rtcp:rtp_rtcp_format",
+    "//third_party/abseil-cpp/absl/types:optional",
   ]
 }
 
@@ -412,7 +412,6 @@
     "..:module_api",
     "../..:webrtc_common",
     "../../:typedefs",
-    "../../api:optional",
     "../../api/video:video_frame",
     "../../api/video_codecs:video_codecs_api",
     "../../common_video",
@@ -422,6 +421,7 @@
     "../../system_wrappers",
     "../../system_wrappers:field_trial_api",
     "../../system_wrappers:metrics_api",
+    "//third_party/abseil-cpp/absl/types:optional",
     "//third_party/libyuv",
   ]
 }
@@ -454,7 +454,6 @@
     "..:module_api",
     "../..:webrtc_common",
     "../../:typedefs",
-    "../../api:optional",
     "../../api/video:video_frame",
     "../../api/video_codecs:video_codecs_api",
     "../../common_video",
@@ -464,6 +463,7 @@
     "../../system_wrappers",
     "../../system_wrappers:field_trial_api",
     "../../system_wrappers:metrics_api",
+    "//third_party/abseil-cpp/absl/types:optional",
     "//third_party/libyuv",
   ]
   if (rtc_build_libvpx) {
@@ -758,7 +758,6 @@
       "../..:webrtc_common",
       "../../api:create_videocodec_test_fixture_api",
       "../../api:mock_video_codec_factory",
-      "../../api:optional",
       "../../api:videocodec_test_fixture_api",
       "../../api/video:video_frame_i420",
       "../../api/video_codecs:rtc_software_fallback_wrappers",
@@ -773,6 +772,7 @@
       "../../test:test_support",
       "../../test:video_test_common",
       "../rtp_rtcp:rtp_rtcp_format",
+      "//third_party/abseil-cpp/absl/types:optional",
     ]
 
     data = video_coding_modules_tests_resources