[WIP] Add FXIOS-10111 Local remote settings records fetching for password generator

[nbhasin2]

📜 Tickets

Jira ticket - 10111
Github issue

💡 Description

After initializing utilities, rules can be fetched like below

let utilities = RemoteSettingsUtilities()
    Task {
        if let passwordRules: [PasswordRuleRecord] = await utilities.fetchLocalRecord(for: .passwordRules) {
            for rule in passwordRules {
                print("Password Rules: \\(rule.passwordRules)")
            }
        }
    }

📝 Checklist

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• Filled in the above information (tickets numbers and description of your work)
• Updated the PR name to follow our PR naming guidelines
• Wrote unit tests and/or ensured the tests suite is passing
• When working on UI, I checked and implemented accessibility (minimum Dynamic Text and VoiceOver)
• If needed, I updated documentation / comments for complex code and public methods
• If needed, added a backport comment (example @Mergifyio backport release/v120)

[nbhasin2]

Slowly moving away from full playground to a more structured approach.

While we wait for caching support from Application Services we can implement the local layer to fetch items from JSON that is shipping to us.

I am opening this PR to gather some thoughts around the structure. Will post in our slack channel as well but feel free to explore this and give feedback.

https://github.com/mozilla-mobile/firefox-ios/pull/21813/files - You can mostly ignore this because its purely for me testing. I will add proper support for debug menu in a separate PR to not bloat this one.

TODOs

• Gather feedback
• Write tests
• Add any missing item / move to browserkit 🤷🏼‍♂️

cc @mattreaganmozilla @issammani