Add warning message about limits at compilation

[glihm]

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Currently, Sozo has some --stats options to display the size of contracts when compiled.

However, this is not something that will emit a warning during compilation, and sometimes it's hard for users to understand why the declaration of a class is failing.

In this issue, the idea is to add a warning message during compilation if we detect:

1. Too big Sierra file (> 4MB)
2. If casm is enabled, too much felts in the byte code (>81920 felts).

Limits reference: https://docs.starknet.io/resources/chain-info/#current_limits.