Support arbitrary unsigned integer attributes (#3591)

Support arbitrary unsigned integer attributes (#3591)

Fixes #3586. On macOS, `size_t` resolves to `unsigned long` whereas `uint64_t`
resolves to `unsigned long long`. Even though the types have the same bit-width
and signedness, they are not considered the same type. This caused issues with
`Attribute`s that store `size_t` values because we only specialized the
`getTable()` struct for `uint64_t`. This commit changes the specialization to
work for arbitrary unsigned integer types of at most 64-bit. It does that by
generalizing the specialization of `getTable()` and by implementing a
`KindValueToTableValueMapping` for unsigned integer attributes of up to 64-bit
that casts integers between the attributes bit-width and `uint64_t`.