Remove legacy Click to Load configuration

[kzar]

The migration away from the legacy social_ctp_configuration.json
configuration for Click to Load is complete. Let's use the new
configuration for the MV2 code paths and remove all references to the
legacy configuration.

While at it, let's also:

• Deprecate the clickToLoadClicks Object that's no longer required
  and remove the corresponding logic.
• Remove the imgToData function that was added for Click to Load but
  no longer used.
• Remove a now unused webNavigation.onCommitted listener that was
  originally needed for Click to Load.
• Rewrite the Click to Load unit tests that were passing
  incorrectly.
• Fix the Click to Load Facebook integration tests, so that they
  aren't marked as pending when blocking fails.

Reviewer: @sammacbeth
Cc: @ladamski, @franfaccin

Steps to test this PR:

1. Ensure the Click to Load integration tests are still passing (for MV2 and MV3).
2. Test that Facebook Click to Load works correctly on the Facebook test page (for MV2).

Automated tests:

• Unit tests
• Integration tests

Reviewer Checklist:

• Ensure the PR solves the problem
• Review every line of code
• Ensure the PR does no harm by testing the changes thoroughly
• Get help if you're uncomfortable with any of the above!
• Determine if there are any quick wins that improve the implementation

PR Author Checklist:

• Get advice or leverage existing code
• Agree on technical approach with reviewer (if the changes are nuanced)
• Ensure that there is a testing strategy (and documented non-automated tests)
• Ensure there is a documented monitoring strategy (if necessary)
• Consider systems implications

[sammacbeth]

Mostly looks good, but I think you've overcomplicated things with the serializable disabledClickToLoadRuleActions. I proposed an alternative.