redo admin structure

[anna-carroll]

Desired structure:

Withdrawal Admin

Permissions

• Can withdraw ETH and ERC20s from Zenith contract.

Setup

• Configured once at contract deploy time.
• Non-transferrable.

Sequencer Admin

Permissions

• Can set/remove Sequencer keys.

Setup

• Configured once at contract deploy time.
• Non-transferrable.

Sequencer Keys

Permissions

• Signature is accepted as a stamp that co-signs block submission by Builders.
• CANNOT set/remove/transfer its role. (See: Sequencer Admin above)

Setup

• Configured any time by Sequencer Admin.