Implement ZamaEthereumConfigInitializable contract

[peersky]

This PR introduces ZamaEthereumConfigInitializable, an abstract contract designed to support EIP-1167 Minimal Proxy Clones (and other proxy patterns) when using the fhevm library.

It allows developers to initialize the FHEVM coprocessor configuration within an initialize() function, solving the issue where configuration is lost because constructors do not execute in the context of a proxy.

Todo:

Constructor ideally should have bool isTesting variable to ensure both local tests & prod follows best practices:

constructor(bool isTesting)
{
   if(!isTesting) disableInitializers();
}

This is in a way breaking API change as current constructor takes no arguments. I just leave it open for maintainers to edit PR and figure out approach.

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