Create execution script for informative vote

[PeterMPhillips]

From DotVoting.sol:

In order to work with a dot vote the execution script must contain
Arrays as its first six parameters. Non-string array lengths must all equal candidateLength
The first Array is generally a list of identifiers (address)
The second array will be composed of support value (uint256).
The third array will be end index for each candidates Information within the infoString (optional uint256)
The fourth array is a string of concatenated candidate information, the infoString (optional string)
The fifth array is used for description params (optional string)
The sixth array is an array of identification keys (optional uint256)
The seventh array is a second array of identification keys, usually mapping to a second level (optional uint256)
The eighth parameter is used as the identifier for this vote. (uint256)

When a new vote gets created the front-end must take the app address, description, and voting options and build the execution script using encodeCallScript function from @aragon/test-helpers