Proxy initialization reentrancy fix

[gabririgo]

Summary

Pool initialization can be reentered.

Motivation

Since during proxy initialization an arbitrary external contract is called, the method could potentially be reentered.

Specification

A non-reentrant modifier should be added to the proxy factory contracts to avoid potential side effects. Since this requires upgrading the factories, we could alternatively apply the modifier to the initialize method in the implementations, where the external contract is called.
The new modifier should use EIP-1553 - transient storage.

Should also check if we want to just use a low-level staticcall when calling an untrusted external contract to read data, as during the initialization.

[gabririgo]

view methods to an external contract execute a staticcall and therefore pool initialization cannot be reentered in the context of rigoblock. Although adding a non-reentrant modifier would future-proof the proxy initialization, there is no apparent need for a non-view call to an external contract during pool initialization, therefore it is pointless to add gas cost to pool deployment.