tvg_loader: introduce tvg interpreter base class for future extension.

tvg_loader: introduce tvg interpreter base class for future extension.

tvg binary format might break the compatibility if any major features have been changed.
It's allowed to do it when the major version is upgraded.

In that case, still we need to support the backward compatibility,
we can provide multiple binary interpreters and choose the proper one
based on the current loading tvg binary format version.

Thus, you can add further interpreters if it's necessary in the future.
Our policy is to derive the TvgBinInterpreterBase class to make it running on
the interface.

for example, if the major version is upgraded 1.x, you can implement TvgBinInterpreter1.