Reland "New video encoder API."

This reverts commit 56e63097498d0ad6fe2eca779b7df173cc6a0fca.

Reason for revert: Preparing for reland

Original change's description:
> Revert "New video encoder API."
>
> This reverts commit 42f12d5183016060dcddc0b515a53294853559fe.
>
> Reason for revert: tests fails downstream
>
> Original change's description:
> > New video encoder API.
> >
> > Also initial implementation wrapping the libaom AV1 encoder.
> >
> > Note that for now this is intended for prototype purposes.
> >
> > Bug: none
> > Change-Id: Iac42ca4aecb6a204601c9f00bfb300e3eda3c4f4
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/306181
> > Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> > Commit-Queue: Philip Eliasson <philipel@webrtc.org>
> > Reviewed-by: Erik Språng <sprang@webrtc.org>
> > Cr-Commit-Position: refs/heads/main@{#42108}
>
> Bug: none
> Change-Id: I927260353afb91df6c7650364baee4f13a098efd
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/347883
> Commit-Queue: Philip Eliasson <philipel@webrtc.org>
> Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
> Reviewed-by: Philip Eliasson <philipel@webrtc.org>
> Owners-Override: Philip Eliasson <philipel@webrtc.org>
> Auto-Submit: Danil Chapovalov <danilchap@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#42111}

Bug: none
Change-Id: Ib72ef5359ead697d27301e2ca2408e8b27165931
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/349001
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42172}
diff --git a/rtc_base/numerics/rational.h b/rtc_base/numerics/rational.h
new file mode 100644
index 0000000..32f0cb1
--- /dev/null
+++ b/rtc_base/numerics/rational.h
@@ -0,0 +1,28 @@
+/*
+ *  Copyright 2024 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef RTC_BASE_NUMERICS_RATIONAL_H_
+#define RTC_BASE_NUMERICS_RATIONAL_H_
+
+namespace webrtc {
+
+// This is the worst implementation of a rational...
+struct Rational {
+  int numerator;
+  int denominator;
+
+  bool operator==(const Rational& other) const {
+    return numerator == other.numerator && denominator == other.denominator;
+  }
+};
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_RATIONAL_H_