Add fallback translation bundle method

[jhugman]

Related to EXP-3042.

The functional part of this is the adding a fallback translation bundle lookup method.

It's actually quite difficult to test, given that there are no strings in the ios megazord, so there exists a duplicate method in Firefox for iOS. We include it here since we want to use it in Focus.

Because Nimbus doesn't know the internal structure of the bundle it can only provide this fallbackTranslationBundle() method— it will be up to the app to provide the list of bundles themselves.

The old way of doing this was to call Nimbus.create(… resourceBundles: [Bundle.main, Strings.bundle] ). The new way of doing this will be:

let bundles = [
   Bundle.main,
   Strings.bundle,
   Strings.bundle.fallbackTranslationBundle(),
].compactMap { $0 }

NimbusBuilder(…)
    .with(resourceBundles: bundles)
    …
    .build()

Pull Request checklist

• Quality: This PR builds and tests run cleanly
  • Note:
    • For changes that need extra cross-platform testing, consider adding [ci full] to the PR title.
    • If this pull request includes a breaking change, consider cutting a new release after merging.
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry in CHANGES_UNRELEASED.md or an explanation of why it does not need one
  • Any breaking changes to Swift or Kotlin binding APIs are noted explicitly
• Dependencies: This PR follows our dependency management guidelines
  • Any new dependencies are accompanied by a summary of the due dilligence applied in selecting them.

Branch builds: add [ff-android: firefox-android-branch-name] and/or [fenix: fenix-branch-name] to the PR title.

[codecov-commenter]

Codecov Report

Base: 46.57% // Head: 46.56% // Decreases project coverage by -0.01% ⚠️

Coverage data is based on head (46ea619) compared to base (b8ba517).
Patch has no changes to coverable lines.

❗ Current head 46ea619 differs from pull request most recent head 8267577. Consider uploading reports for the commit 8267577 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5314      +/-   ##
==========================================
- Coverage   46.57%   46.56%   -0.02%     
==========================================
  Files         180      180              
  Lines       14449    14450       +1     
==========================================
- Hits         6729     6728       -1     
- Misses       7720     7722       +2     

Impacted Files	Coverage Δ
.../support/rc_crypto/nss/nss_build_common/src/lib.rs	66.33% <0.00%> (-0.67%)	⬇️
components/nimbus/src/behavior.rs	89.83% <0.00%> (-0.41%)	⬇️

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[jeddai]

Looks good to me!

[jeddai]

I'm not familiar with this code format, could you briefly explain what's happening here?

[jhugman]

Sure. Swift has named arguments as part of the name of the method, and the Swift trend has been to embrace that, so now we write:

builder.with(errorReporter: theReporter)

instead of:

builder.withErrorReporter(theReporter)

The syntax above is:

func methodName(namedArg localName: Type)

where namedArg is _, then it's omitted when calling (like withErrorReporter(theReporter)).
and localName is optional, and that's the name of the argument in the method.

func methodName(namedArg localName: Type) {

}

is syntactic sugar for:

func methodName(namedArg: Type) {
   let localName = namedArg

}

Let me know if this does/doesn't help.