Reland of Add optional visualization file writers to VideoProcessor tests. (patchset #1 id:1 of https://codereview.webrtc.org/2708103002/ )

Reason for revert:
Necessary calls were "protected" by RTC_DCHECKs, that were optimized away in some release builds.
Replacing the RTC_DCHECKs with EXPECTs.

Original issue's description:
> Revert of Add optional visualization file writers to VideoProcessor tests. (patchset #4 id:220001 of https://codereview.webrtc.org/2700493006/ )
>
> Reason for revert:
> Breaks downstream project.
>
> Original issue's description:
> > Add optional visualization file writers to VideoProcessor tests.
> >
> > The purpose of this visualization CL is to add the ability to record
> > video at the source, after encode, and after decode, in the VideoProcessor
> > tests. These output files can then be replayed and used as a subjective
> > complement to the objective metric plots given by the existing Python
> > plotting script.
> >
> > BUG=webrtc:6634
> >
> > Review-Url: https://codereview.webrtc.org/2700493006
> > Cr-Commit-Position: refs/heads/master@{#16738}
> > Committed: 872104ac41
>
> TBR=asapersson@webrtc.org,sprang@webrtc.org,kjellander@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:6634
>
> Review-Url: https://codereview.webrtc.org/2708103002
> Cr-Commit-Position: refs/heads/master@{#16745}
> Committed: 2a8135a174

TBR=asapersson@webrtc.org,sprang@webrtc.org,kjellander@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
BUG=webrtc:6634

Review-Url: https://codereview.webrtc.org/2706123003
Cr-Commit-Position: refs/heads/master@{#16769}

webrtc/modules/video_coding/BUILD.gn

@@ -351,6 +351,7 @@ if (rtc_include_tests) {
     deps = [
       ":video_codecs_test_framework",
       ":video_coding",
+      ":video_coding_utility",
       ":webrtc_h264",
       ":webrtc_vp8",
       ":webrtc_vp9",