Add --exclude-paths flag to filesystem module

[JosiahOne]

Description

Like https://github.com/trufflesecurity/trufflehog/issues/420 but for the filesystem module.

Problem to be Addressed

We frequently use the filesystem module to scan large amounts of code. There are many directories we'd like to exclude for a variety of reasons (but the most common being test data that has intentional creds) and we were hoping we could creating a file to ignore these directories just like when using the git module.

Unfortunately, it seems the --exclude-paths flag is unavailable for filesystem scanning.

Description of the Preferred Solution

Provide --exclude-paths using exactly the same interface as the git module.