Autoplay refactor

[darkdh]

1. Move autoplay to site settings
2. Introduce built-in site settings

fix #8847

Auditors: @bbondy, @bsclifton

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Test Plan:
Covered by webdriver test and unit test

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run indivually or as a suite ref

[darkdh]

working on test

[darkdh]

Please provide built-in site settings list to support js/data/siteSettingsList.js

[bbondy]

nit: pls remove this commented out code

[bbondy]

++