Move stream options and frame output structs to dedicated headers

[dvrogozh]

Fixes: #618

Commit moves stream options and frame output structs to dedicated headers:

• Frame.h now defines FrameOutput, FrameBatchOutput and AudioFrameOutput
• Stream.h now defines VideoStreamOptions, AudioStreamOptions, StreamMetadata and ContainerMetadata

Commit also resolves circular dependency between DeviceInterface.h and SingleStreamDecoder.h, forward declaration of class DeviceInterface no longer needed.

CC: @scotts, @NicolasHug

[NicolasHug]

Thanks for the PR @dvrogozh . Was it necessary to move the StreamMetadata and ContainerMetadata classes into this new header?
If yes, then I'd suggest moving them into their own metadata.h header
If not, then it might be best to leave them in the SingleStreamDecoder files

In both cases, I'd also suggest to rename Stream.h into just StreamOptions.h since this file should only contain option-related structs.

Otherwise, this PR LGTM

[scotts]

Agreed with @NicolasHug - if we need to move the metadata definitions, let's put them in their own file. If we don't need to, let's leave them be for now. And also agreed on naming.

[dvrogozh]

In the last update I've pushed:

• Stream.h renamed to StreamOptions.h
• Created Medata.h to hold StreamMetadata and ContainerMetadata

@NicolasHug , @scotts : The reason why I moved metadata to header was that StreamMetadata is used by FrameBatchOutput which I also moved:

torchcodec/src/torchcodec/_core/SingleStreamDecoder.h

Lines 181 to 184 in 8b19f45

	explicit FrameBatchOutput(
	int64_t numFrames,
	const VideoStreamOptions& videoStreamOptions,
	const StreamMetadata& streamMetadata);

That being said, note that I moved ContainerMetadata only for consistency - it's not used by any of the structures we really need to be in headers. Let me know if you want to avoid moving ContainerMetadata. Also, if we don't want to separately expose FrameBatchOutput we can avoid moving metadata to separate header entirely.

[scotts]

@dvrogozh, looks good, thanks for cleaning this up!