Feature Request: Split single file verifications into different files.

Some contracts on Etherscan get verified as a single flat file making it hard to navigate them.

Here is a random example I took from the Etherscan's list of verified contracts.
https://etherscan.io/address/0x38b1c1be183a480835e9bc63c5acfd18eedd1cb0#code

I believe that can be accomplished by splitting the files at the terms:

- contract
- library
- abstract
- interface

The simply generating the import statements in each file for every other file even if not used as well as pragma statement for solidity version. Given they are all in same directory that is possible.

Given that the original file is flattened (does not have imports) that could work and will help study the contract better even if a few extra imports are generated. I assume those will be highlighted in VSCode.

Start by tracing the Etherscan contract-verification flow and how flattened Solidity source is currently handled; the issue names no implementation files or tests. Define completion as producing separate files at contract, library, abstract, and interface declarations, with the Solidity pragma and generated imports present in each file.

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