Add FXIOS-11168 [Content Sharing Opt] Telemetry to track start up time for deeplinks (backport #24422)

[mergify]

📜 Tickets

Jira ticket
Github issue

💡 Description

Added Telemetry to track start up time when opening a deep link. Refactor ShareTelemetry to include method for measuring startup time. Adjusted ShareActivityTelemetryItemProviderTests with refactored ShareTelemetry.

📝 Checklist

You have to check all boxes before merging

• 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)

---

This is an automatic backport of pull request #24422 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of d17d22b has failed:

On branch mergify/bp/release/v135/pr-24422
Your branch is up to date with 'origin/release/v135'.

You are currently cherry-picking commit d17d22be9.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   firefox-ios/Client.xcodeproj/project.pbxproj
	modified:   firefox-ios/Client/Application/SceneDelegate.swift
	modified:   firefox-ios/Client/Coordinators/Browser/BrowserCoordinator.swift
	modified:   firefox-ios/Client/Frontend/Browser/Event Queue/AppEvent.swift
	modified:   firefox-ios/Client/Frontend/Share/ShareTelemetry.swift
	modified:   firefox-ios/Client/Frontend/Share/ShareTelemetryActivityItemProvider.swift
	modified:   firefox-ios/Client/metrics.yaml
	modified:   firefox-ios/firefox-ios-tests/Tests/ClientTests/Mocks/MockBrowserViewController.swift
	deleted:    firefox-ios/firefox-ios-tests/Tests/ClientTests/Sharing/Mocks/MockShareTelemetry.swift
	modified:   firefox-ios/firefox-ios-tests/Tests/ClientTests/Sharing/ShareTelemetryActivityItemProviderTests.swift
	modified:   firefox-ios/firefox-ios-tests/Tests/ClientTests/Sharing/ShareTelemetryTests.swift

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   firefox-ios/Client/Application/AppDelegate.swift
	both modified:   firefox-ios/Client/Frontend/Browser/BrowserViewController/Views/BrowserViewController.swift

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally