Investigate ReentrancyGuard initialization

[minghinmatthewlam]

Context and scope
Right now in the ReentrancyGuards that Teleporter messenger uses, there are state variables initialized in the constructor of the contract. If the Teleporter deploy tx fails, then the work around as discussed in this bug is to use a state upgrade, and the state upgrade would also need to set the specific values for _sendEntered and _receiveEntered storage slots. We can look at moving that logic outside of the constructor so that we don't need to set the value for specific storage slots, or should at least have documentation for these steps.

Discussion and alternatives
Look at alternative to setting reentrancy state variable initial values than from setting in constructor. At least document steps to set storage slot upgrades.

Related to #306