Add new Timing block to app loading track message

[lbwexler]

Add new Timing block to app loading track message.

• New state for 'Authenticating'
• Misc cleanups

Hoist P/R Checklist

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• [X] Caught up with develop branch as of last change.
• [X] Added CHANGELOG entry, or determined not required.
• [X] Reviewed for breaking changes, added breaking-change label + CHANGELOG if so.
• [X] Updated doc comments / prop-types, or determined not required.
• [X] Reviewed and tested on Mobile, or determined not required.
• [X] Created Toolbox branch / PR, or determined not required.

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[lbwexler]

Went for the suggested additional states. Think we should go ahead and leverage all this, and I doubt anyone was observing it specifically.