(re)Add support for ast only file

[montyly]

With crytic/slither#823, we removed the support for AST-only file in Slither.

We could re-add this support by adding a ast-only platform in crytic-compile.

Ideally the contract is compiled with abi,ast,bin,bin-runtime,srcmap,srcmap-runtime,userdoc,devdoc,hashes,compact-format, but we could allow a best-effort approach here.

The main difficulty that I can see here is that Slither now relies more on the source code being accessible, so we might need to disable some analyses in Slither.

Related crytic/slither#864

[yann300]

@montyly is this still something planned?

[joaquinlpereyra]

Voicing support for this to be re-enabled, as it allows for some quick-and-dirty analysis of some interesting properties. A very good usecase: if a bug is found on a widely used library, a quick detector could be written on slither to look for the vulnerability in contracts in smart-contract-sanctuary.

These contracts do not compile, but their AST can be generated.