feat: better support for cookies

[sehnryr]

Proposed changes

Better cookies management with the help of a Map like CookieJar and Cookie that will store all the data of the cookies.

Better cookies parsing algorithm.

Should fix #44 and #48.

Type of changes

What types of changes does your code introduce?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have read the CONTRIBUTING doc
• My code follows the Dart coding convention
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works.
• I have commented my code, particularly in hard-to-understand areas
• I have added necessary documentation (if appropriate)

Further comments

The algorithm works assuming there will not be any commas in keys or values of a cookie.