task(passkeys): Use AppErrors instead of passkey.errors.ts

[dschom]

Because

• We want to use AppErrors to simplify error handling

This pull request

• Removes passkey.errors.ts
• Ports errors over to AppError
• Updates references
• Adds some metrics to go along with errors

Issue that this pull request solves

Closes: FXA-13303

Checklist

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• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).
• I have manually reviewed all AI generated code.

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[nshirley]

r+wc, just two minor things. I can deal with the conflicts 😅