Replace rtc::Optional with absl::optional in modules/audio processing

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

This CL generated by running script with parameter 'modules/audio_processing'

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: Id29f8de59dba704787c2c38a3d05c60827c181b0
Reviewed-on: https://webrtc-review.googlesource.com/83982
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23653}

modules/audio_processing/test/audioproc_float_impl.cc

@@ -184,19 +184,19 @@ DEFINE_string(aec3_settings,
 DEFINE_bool(help, false, "Print this message");
 
 void SetSettingIfSpecified(const std::string& value,
-                           rtc::Optional<std::string>* parameter) {
+                           absl::optional<std::string>* parameter) {
   if (value.compare("") != 0) {
     *parameter = value;
   }
 }
 
-void SetSettingIfSpecified(int value, rtc::Optional<int>* parameter) {
+void SetSettingIfSpecified(int value, absl::optional<int>* parameter) {
   if (value != kParameterNotSpecifiedValue) {
     *parameter = value;
   }
 }
 
-void SetSettingIfFlagSet(int32_t flag, rtc::Optional<bool>* parameter) {
+void SetSettingIfFlagSet(int32_t flag, absl::optional<bool>* parameter) {
   if (flag == 0) {
     *parameter = false;
   } else if (flag == 1) {