Manifest V2 deprecation

[sudonims]

Manifest V2 extensions will no longer work on chrome starting next year. deprecation notice

Work to do:

1. Upgrade manifest to V3
2. This upgrade changes the way background scripts work (like a service instead a constant background script) Most of the background.js code should be good enough, will need to do testing
3. Host permission should be looked into

[sudonims]

@whoanuragverma , You can self assign when you are free from CATs...