EIP-712: Update assets to show array encoding

[bitpshr]

This pull request updates the example assets for EIP-712 to include support for array encoding per the specification:

The array values are encoded as the keccak256 hash of the concatenated encodeData of their contents (i.e. the encoding of SomeType[5] is identical to that of a struct containing five members of type SomeType).

cc @recmo

[bitpshr]

Hi @recmo. Did you have a chance to check if this array encoding implementation matches your intention with the proposal? Thanks in advance.

[mckingho]

Good to see an implemention on encoding array data. Thank @bitpshr.
I think this implementaion does not support array of primitive type. I am trying to add a new field in Person object. The field is an array of primitive data type, uint256[]. But it encounters error - TypeError: Cannot read property 'map' of undefined.
The function encodeData is an implementation of encoding 'struct' and the script fails when a primitive type is passed as primaryType in function encodeType.