Reland "[DVQA] Create separate BUILD.gn file for video analyzer"

This reverts commit 76793c300fdd87fa8fd8be3dd2e5faf8c1916e96.

Reason for revert: Can't cleanly revert the old one. A forward fix will be provided.

Original change's description:
> Revert "[DVQA] Create separate BUILD.gn file for video analyzer"
>
> This reverts commit 116c0a53d4a35c6dee857eb4cc2b6ae233a0427c.
>
> Reason for revert: Breaks bot: https://ci.chromium.org/ui/p/chromium/builders/try/linux_chromium_compile_dbg_ng/1415352/overview
>
>
> Original change's description:
> > [DVQA] Create separate BUILD.gn file for video analyzer
> >
> > Bug: None
> > Change-Id: I37dd2262bf3f52b2f5abe7934b9c41eaa27ffd17
> > No-try: True
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/283141
> > Commit-Queue: Artem Titov <titovartem@webrtc.org>
> > Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> > Cr-Commit-Position: refs/heads/main@{#38662}
>
> Bug: None
> Change-Id: Ieeb8c569560cb9d60d0c4d3c1268fa57f56b8157
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/284000
> Auto-Submit: Ilya Nikolaevskiy <ilnik@webrtc.org>
> Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#38672}

Bug: None
Change-Id: I74506eaa6a1060bf87e651881c86b4f576f447ec
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/284020
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38676}