Implemented Linting & Testing

I added the basic linting logic and I tested if it works.
As you can see in the video, linting works nicely and it successfully returns the matches.

Here’s the example rule set I used in the video:

name: basic-ruleset
description: This is a basic ruleset.
version: 1

rules:
  - id: no-hello
    message: '"hello" is not allowed.'
    severity: error
    checker: std.regex
    args:
        pattern: hello

  - id: invalid-hello
    message: '"helloooo" is not allowed.'
    severity: error
    checker: std.regex
    args:
        pattern: helloooo