Read underlying errors recursively

[samsymons]

Task/Issue URL: https://app.asana.com/0/414235014887631/1208811744276031/f
Tech Design URL:
CC:

Description:

This PR updates the pixel error handling to read underlying errors recursively.

Steps to test this PR:

1. Check that the test suite changes cover everything correctly and that no pixel behavior is otherwise changing
2. Next, we can check that this works with a pixel by adding a test call that uses many underlying errors. Add the following to the bottom of applicationDidBecomeActive:

let underlyingError4 = NSError(domain: "underlyingError4", code: 5, userInfo: [:])
let underlyingError3 = NSError(domain: "underlyingError3", code: 4, userInfo: [NSUnderlyingErrorKey: underlyingError4])
let underlyingError2 = NSError(domain: "underlyingError2", code: 3, userInfo: [NSUnderlyingErrorKey: underlyingError3])
let underlyingError1 = NSError(domain: "underlyingError1", code: 2, userInfo: [NSUnderlyingErrorKey: underlyingError2])
let error = NSError(domain: "error", code: 1, userInfo: [NSUnderlyingErrorKey: underlyingError1])

Pixel.fire(pixel: .networkProtectionRekeyFailure, error: error)

Then, run the app and filter for rekey, and check that the parameters look good.

Definition of Done (Internal Only):

• Does this PR satisfy our Definition of Done?

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

[diegoreymendez]

This is fantastic! Thanks @samsymons