This fixes some errors where too many bytes were allowed to be read for
signed integers of a smaller size (e.g. i32). The new parser doesn't
make 64-bit assumptions and now matches the generality of its unsigned
counterpart.
Pretty much no other read function does this, and getting rid of the
typename template parameter for the stream makes the transition to the
new AK::Stream a bit easier.
This patch adds the `USING_AK_GLOBALLY` macro which is enabled by
default, but can be overridden by build flags.
This is a step towards integrating Jakt and AK types.
Previously, we would go crazy and shift things way out of bounds.
Add tests to verify that the decoding algorithm is safe around the
limits of the result type.
