Add SCC support for CEA-708 Decoder

[voidash]

In raising this pull request, I confirm the following (please check boxes):

• I have read and understood the contributors guide.
• I have checked that another pull request for this purpose does not exist.
• I have considered, and confirmed that this submission will be valuable to others.
• I accept that this submission may not be used, and the pull request closed at the will of the maintainer.
• I give this submission freely, and claim no ownership to its content.
• I have mentioned this change in the changelog.

My familiarity with the project is as follows (check one):

• I have never used CCExtractor.
• I have used CCExtractor just a couple of times.
• I absolutely love CCExtractor, but have not contributed previously.
• I am an active contributor to CCExtractor.

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When SCC was extracted from MOV file, the SCC file was empty. So in order to fix that this pull request is being made. The exact issue it fixes is #1426 .Now SCC can be extracted from the sample video provided in the issue. Also It might be worth mentioning that the SCC caption type is pop on.

[PunitLodha]

Please fix the formatting issues by running clang-format and rustfmt

[ArchitBhonsle]

Any idea why this PR isn't merged? Is there some work left?

[cfsmp3]

Any idea why this PR isn't merged? Is there some work left?

If I remember correctly, @voidash disappeared

[PunitLodha]

Any idea why this PR isn't merged? Is there some work left?

@ArchitBhonsle If you test this PR, you'll see that the SCC header is being repeated for each subtitle line

[cfsmp3]

Closing since @voidash seems to have vanished and there's merge conflicts and @IshanGrover2004 has been working on this anyway.