feat: ProtocolHandler

[obatirou]

Part of #1515
The owner of the Kakarot contract will be an intermediary contract: the ProtocolHandler.

This PR introduce the structure of the contract and implements the Admin functions:

fn emergency_execution(ref self: TContractState, call: Call);
fn upgrade(ref self: TContractState, new_class_hash: ClassHash);
fn transfer_ownership(ref self: TContractState, new_owner: ContractAddress);
fn soft_pause(ref self: TContractState);
fn hard_pause(ref self: TContractState);
fn unpause(ref self: TContractState);

Time spent on this PR:

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Resolves #

What is the new behavior?

ProtocolHandler contract

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This change is