This commit refactors `Table` in the runtime such that it can be created from a
pointer to existing table data.
The current `Vec` backing of the `Table` is considered to be "dynamic" storage.
This will be used for the upcoming pooling allocator where table memory is
managed externally to the instance.
The `table.copy` implementation was improved to use slice primitives for doing
the copying.
Fixes#983.
f0d93d102c