Remove concept of shares from client-returned delegations

[alexanderbez]

The concept of "shares" has been removed from client facing bonding/unbonding actions (#3857). However, delegations and re-delegations still return the notion of "shares" -- they should return tokens.

Acceptance Criteria:

TODO

Shares is still a core component of both the RedelegationEntry and Delegation types. So I'm not totally sure of the best course of action here. We can add a new field, amount, but that would increase state bloat. Or, we can implement a new type just for clients that does the conversion after we fetch the objects.

/cc @faboweb @fedekunze

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[faboweb]

I would create an only client facing type that adds the amount field.
After some versions I would even remove the shares completely from the client facing type. But only after some versions to improve upgradability.

Thx for taking care of this.