Reland "Refactor NetEq delay manager logic."

This is a reland of f8e62fcb14e37a5be4f1e4f599d34c8483fea8e9

Original change's description:
> Refactor NetEq delay manager logic.
>
> - Removes dependence on sequence number for calculating target delay.
> - Changes target delay unit to milliseconds instead of number of
>   packets.
> - Moves acceleration/preemptive expand thresholds to decision logic.
>   Tests for this will be added in a follow up cl.
>
> Bug: webrtc:10333
> Change-Id: If690aae4abf41ef1d9353f0ff01fb7d121cf8a26
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186265
> Commit-Queue: Jakob Ivarsson <jakobi@webrtc.org>
> Reviewed-by: Ivo Creusen <ivoc@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#32326}

Bug: webrtc:10333
Change-Id: Iad5e7063f63b84762959ee5b412f5f14a7b2cd06
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186943
Commit-Queue: Jakob Ivarsson <jakobi@webrtc.org>
Reviewed-by: Ivo Creusen <ivoc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32332}

modules/audio_coding/neteq/decision_logic_unittest.cc

@@ -43,6 +43,6 @@ TEST(DecisionLogic, CreateAndDestroy) {
   logic->SetSampleRate(fs_hz, output_size_samples);
 }
 
-// TODO(hlundin): Write more tests.
+// TODO(jakobi): Write more tests.
 
 }  // namespace webrtc