Fix coursera-dl to work and major tweaks

Fix:

• fix .unescape error in Python 3.9 and above
• fix course outline pasing error
• fix syntax error
• fix unit test
• fix login failed error

Features:

• add --browser-cookie argument to specify automatically extract CAUTH value from the browser cookie.
• add support for login using browser, and --headless argument can be used to contronl.
• add github actions workflow to run unit test

Refactor:

• rename project
• update python version of support
• move test