Smart contract cannot give up Committee update rights, nor receive one

[villesundell]

Describe the bug
Current code requires authorizations from both, the current owner of Committee update rights, and the receiver of these rights. Although this is a clever way to check the account really exists, it's not feasible with smart contracts, which would need to have rights to each other, since transaction authorizations cannot be forwarded.

Expected behavior
Account currently owning the Committee update rights, should be able to assign any account, including a contract account.

Additional context
The problematic line is here:

telos-decide/contracts/decide/src/committee.cpp

Line 117 in b17261e

require_auth(permission_level{updater_account, updater_auth});