Convert baseline file to match local filesystem path

[eddiez9]

Problem
Currently, detect-secrets doesn't support multi OS environments very well.

If a Windows developer generates a baseline file, Linux developers will always be alerted on new secrets and vice versa.

This is because baseline files have OS specific paths

Windows:
"filename": "src\blah\appsettings
Linux:
"filename": "src/blah/appsettings

When performing new_secrets = secrets - args.baseline you will always get new secrets because the filenames dont match.

Solution
The best solution would probably be to generate baseline files/read files in a consistent manner to always use Unix paths with something like os.path.normpath Doing this however will mean people will need to update their baseline files.

The solution implemented in the PR instead will using os.sep to determine if we are on UNIX or Windows, then replace slashes in filenames for the loaded baseline file (without changing the baseline file). The comparison will then work regardless of if you are on Linux comparing against a windows generated baseline file and vice versa.

[eddiez9]

Hey there, requesting any feedback on this PR
@lorenzodb1 @jpdakran

[lorenzodb1]

Hi @eddiez9, thank you for opening this PR.

Looks like tests are failing. I'd appreciate if you could take a look and get them all passing.

[eddiez9]

I've had to change the unit tests as they make assumptions about UNIX pathing wrt. assertions.

To summarize all the changes:
core/potential_secret.py
core/secrets_collection.py
Changed to convert paths to the local file system path seperator for secrets via scans but also via baseline files.

util/path.py
convert to local os path function

tests/audit/audit_test.py
change assertion to use os.path.join instead of hardcoded /

tests/pre_commit_hook_test.py
tests/core/secrets_collection_test.py
change assertions to use os.path.join instead of hardcoded /

tests/core/baselien_test.py
this failing test checks we can read a baseline file and output it exactly the same.
this fails on windows after the path conversion so i've added a check to replace slashes if run on Windows. Another solution for this could potentially have a seperate secrets.baseline.windows file that has windows paths but this complicates pre-commit exclusions