fix!: gathered_filter to process regex correctly

[alperenkose]

Description

Regex expressions in gathered state gathered_filter required extra escape chars which wasn't a valid regex in deed.
This PR allows to write valid regex expression in the gathered_filter, the previous syntax is not valid anymore hence this is introducing a breaking change.

shlex.split() was used to split logic expressions in the gathered_filter, which also escaped(removed) backslash \ chars from the expression and led to a non-working regex. We have implemented our split method using shlex but removing backslash(\) escape char from shlex instance to avoid escaping and properly processing regex expressions.

Motivation and Context

Fixes #579

How Has This Been Tested?

Tested on vm firewalls with examples in the issue.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes if appropriate.
• All new and existing tests passed.

[horiagunica]

👍