Support for arbitrary contract storage base location

[matheusaaguiar]

This is the list of steps required to support the specification of arbitrary contract storage base locations.
There's already a long discussion in (previous) issue #597, which provided the basis for the syntax and behavior, recorded here: Initial syntax for explicit storage locations

Tasks

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1. Syntax/Parsing support: Parser support for explicit storage locations #15463
2. Type checking (analysis): Type checking for contract explicit storage base location #15528
3. Add builtin function erc7201
4. Adjust storage layout output to properly show variable slots: Adjust storage layout to consider explicit storage base location #15668
5. AST JSON import/export support
6. Legacy Codegen
7. Yul Codegen
8. Documentation