the add-propoals.ts script can only yet handle /agoric.swingset.CoreEvalProposal.

add support for /cosmos.staking.v1beta1.MsgUpdateParams style proposals

the proposal package should include information about the proposal pulled from an RPC node. For example, https://github.com/Agoric/agoric-3-proposals/pull/286/files#diff-4e47acaf05714834f62d75bbe4c6ff47f24fc37c451c5f3c0db29c52d0d9fa1a