get color values for all bgs

[ben-c-at-moz]

Relevant Links

Bugzilla: Link

Description of Code / Doc Changes

• Reenable test
• Add method to check if theme color is "close enough" to the key

Process Changes Required

None

Screenshots or Explanations

The current AboutAddons.activate_theme contains a perform_assert check to ensure that the theme was applied successfully. We need to not do that so we can use our "close enough" method.

Comments or Future Work

Do we need to start another PR soon to address something you saw while working on this?

I think it would be worthwhile to consider removing the theme color assertion in AboutAddons.activate_theme() and update all relevant tests.

Workflow Checklist

• Please request reviewers
• If asked to address comments, please resolve conversations.
• If asked to change code, please re-request review from the person who wanted changes.

Thank you!

[Tracy-Walker]

lgtm