GH-2258: Preserve user onboarding settings

[leuryr]

Keeps user settings for Blocking and Default Search when the user returns to those screens with Back.

• Adds blockSetupSeen and searchSetupSeen to Redux in order to track if the user has previously visited the settings page and the old selections should be displayed, in addition to respective actions to update them.
• Changes some of the Redux keys in order to prevent any issues when pulling in state through props that have the same key names

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• Have you followed the guidelines in CONTRIBUTING.md?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you added an explanation of what your changes do?
• Does your submission pass tests?
• Did you lint your code prior to submission?

[wlycdgr]

Lemme know if you have any questions on the comments! Two other quick things for the BlockSettingsView:

• "Recommended Choices" checkbox should be checked if the user's choices match what is recommended
• "Recommended Choices" checkbox should become unchecked if the user changes their choice such that they no longer exactly match the recommended settings (this one isn't specific to this PR but would just be a nice bit of cleanup while we're at it)

[wlycdgr]

Just a couple more changes!

[wlycdgr]

LGTM!