Multisig to 5/10 OC members plus AO

Change the multisig signers to be the Operating Committee members, including the Operator (9), plus the Assistant Operator (1), and to require a minimum of five signers to approve a transaction (5/10).

This will further decentralize LexDAO to pass treasury control to a group of publicly known OC members who have affirmed that they will abide by the constitution and operating system.

The multisig signers will be modified in the future with updates to the OC membership, currently scheduled as a quarterly 3 out, 3 in.