Add logic for new Claims type to cw20 staking service

[abefernan]

• Add logic for claiming ready claims.
• Make use of new type of Claims:

interface Claim {
  readonly amount: string;
  readonly released: { readonly at_time: number };
}

export interface Claims {
  readonly claims: readonly Claim[];
}

instead of:

interface Claims {
  readonly claims: number;
}