Only attempt to refresh auth token when user is authenticated

[miasma13]

Task/Issue URL: https://app.asana.com/0/414709148257752/1208966018277167/f

Description:
Following Increase of 401s in auth api - Darwin we found that the refreshAuthTokenIfNeeded is being called without a proper check if user is authenticated (and tokens are present).

It also includes BSK check -> duckduckgo/BrowserServicesKit@fb809ed

Steps to test this PR:

1. Ensure no PP is on the device
2. Open PP purchase page
3. Check if refreshAuthTokenIfNeeded was not called and no calls to validate_token endpoint were made.
4. Purchase or activate subscription
5. Open add/edit email page
6. Check if refreshAuthTokenIfNeeded was properly called with a call to validate_token endpoint.

Definition of Done (Internal Only):

• Does this PR satisfy our Definition of Done?

Copy Testing:

• Use of correct apostrophes in new copy, ie ’ rather than '

Orientation Testing:

• Portrait
• Landscape

Device Testing:

• iPhone SE (1st Gen)
• iPhone 8
• iPhone X
• iPhone 14 Pro
• iPad

OS Testing:

• iOS 15
• iOS 16
• iOS 17

Theme Testing:

• Light theme
• Dark theme

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Internal references:

Software Engineering Expectations
Technical Design Template

[bwaresiak]

LGTM