Add marker sensor to CUPS integration

[Matte23]

Description:

Added marker sensor to CUPS integration. This sensor represent the percentage of ink / toner of configured printers.

Pull request with documentation for home-assistant.io (if applicable): home-assistant/home-assistant.io#9820

Example entry for configuration.yaml (if applicable):

sensor:
  - platform: cups
    printers:
      - C410
      - C430

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly. Update and include derived files by running python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

[ghost]

Hey there @fabaff, mind taking a look at this pull request as its been labeled with a integration (cups) you are listed as a codeowner for? Thanks!

This is a automatic comment generated by codeowners-mention to help ensure issues and pull requests are seen by the right people.