feat!: reimplement multisignature transactions

[Erigara]

Description

This PR provide an example how multisignature transactions could be implemented using iroha triggers.
In this PR i've tried to make as small invasive changes into the core as possible.

How this work?

There is 2 triggers (thanks @s8sato for inspiration in account activation feature):

1. multisig_register - responsible for registering new multisig user and trigger multisig
2. multisig - responsible for executing instructions on behalf of multisig user when enough votes are collected

Assumptions:

• user have to come up with they own public key for multisig account:
  • it might be ok to have primary private key in case of emergency or smt
  • it could be generated at random or obtained through key aggregation
  • it's currently not possible to generate public key inside wasm smart-contracts
• multisig_register should be registered either as part of genesis or by domain owner to have enough permissions for it's actions
  • currently in default executor there is no way to allow certain trigger to be executable by anyone (workaround would be to have trigger which would grant this permission on account registration)

Linked issue

Closes #4373

Benefits

Get back multisig functionality without too much changes on iroha side.

Downsides

Executing multisig instructions through tirgger probably slower that backed in solution.

[mversic]

great piece of work. It would be interesting to explore whether we can make a custom instruction for MultiSigRegister, might be even simpler to use

[Erigara]

great piece of work. It would be interesting to explore whether we can make a custom instruction for MultiSigRegister, might be even simpler to use

i think it should be possible, in this case we would move logic of multisig register trigger into the executor which would be triggered on custom instruction