Since containerd is not using gogo anymore it seems like we should
remove the depenency on gogo here since gogo is a fairly large
dependency and is also unaintained.

This also gets imported by the runc shim and adds a fair amount to the
binary size (in terms of percentage of the whole size).

I did keep a fallback test in that still imports gogo and continues to
work. The test marshals a type with gogo and then unmarshals it by
typeurl.
This is why gogo is still in the go.mod
Not sure if this is worthwhile or not.

This may need a module version bump since some functions will behave
differently now.

Signed-off-by: Brian Goff <[email protected]>

A handler is an unexported type that is used to abstract external type
registries, such as gogoproto.
This allows us to add back gogo support but allow those who don't need
it to compile it out with the `!no_gogo` build tag.

Signed-off-by: Brian Goff <[email protected]>