Shared Signer Mapping

[nlordell]

This PR changes the behaviour of the shared signer to store its configuration as if it were behind a mapping where the key is the shared signer address. This allows multiple shared signer instances to be configured for a single account (in case you ever need to deploy a 2/2 Safe owned by passkeys with 4337).

I created an "accessor" contract to prove that the storage location is indeed the equivalent to a mapping(address self => Signer).

[nlordell]

Do not merge until the Certora audit is complete.

[coveralls]

Pull Request Test Coverage Report for Build 9380824990

Details

• 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 9380559112:	0.0%
Covered Lines:	149
Relevant Lines:	149

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💛 - Coveralls