Andymck/reward manifest additions

[andymck]

This is an attempt to include the rewards per share in the rewards manifests.

The fields are represented as string types in this draft in an attempt to include the same precision in the protos as that used in the internal rewarder calculations. In the rewarder these values are represented as Decimal types.

On the IOT side the rewards per share values are rounded to a precision of 15. On the mobile side no rounding takes place and we end up with decimal value such as

dec!(1713882.1655472017013743978648)

If the corresponding proto field is represented as a float or double this corresponds to a f64 in rust and as such when going from the rewarder's internal decimal value to an f64 we will loose precision on the mobile rewards side. Any consumers of those protos will not be able to arrive at the same final reward values as the mobile rewarder generated.

Alternative options to consider:

1. Represent the proto fields as floats, ignore any loss on the mobile values when going from decimal to float
2. Refactor mobile rewarder to use a default precision same as IOT ( 15 ), represent the proto types as floats. This results in no loss of precision between internal rewarder values and external proto values
3. Other?