Add configuration option to specify slither target

[RaoulSchaffranek]

Hi everyone!

Maybe I don't know where to look, but it seems to me that there is currently no option to specify the target directory for slither. I can run slither from my CLI with slither src where src is the target-folder containing the Solidity files. But the VSCode extension is always trying to run slither . which will ultimately throw the following error:

⸻ Starting analysis ⸻
Error: Error in workspace "/home/raoul/project":
Traceback (most recent call last):
  File "/home/raoul/.local/lib/python3.8/site-packages/slither/__main__.py", line 743, in main_impl
    ) = process_all(filename, args, detector_classes, printer_classes)
  File "/home/raoul/.local/lib/python3.8/site-packages/slither/__main__.py", line 73, in process_all
    compilations = compile_all(target, **vars(args))
  File "/home/raoul/.local/lib/python3.8/site-packages/crytic_compile/crytic_compile.py", line 637, in compile_all
    compilations.append(CryticCompile(target, **kwargs))
  File "/home/raoul/.local/lib/python3.8/site-packages/crytic_compile/crytic_compile.py", line 117, in __init__
    self._compile(**kwargs)
  File "/home/raoul/.local/lib/python3.8/site-packages/crytic_compile/crytic_compile.py", line 548, in _compile
    self._platform.compile(self, **kwargs)
  File "/home/raoul/.local/lib/python3.8/site-packages/crytic_compile/platform/hardhat.py", line 87, in compile
    os.listdir(build_directory), key=lambda x: os.path.getmtime(Path(build_directory, x))
FileNotFoundError: [Errno 2] No such file or directory: 'artifacts/build-info'


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The problem seems to be the following line, which passes . as the hardcoded target to slither:

https://github.com/crytic/slither-vscode/blob/9cbf906ebac9ef9b61964609beda17a646b0bac7/src/slither.ts#L101

It would be nice to have a workspace-folder configuration option to specify the target manually.