[CI] Improve linters and git hooks

[testableapple]

Resolve https://linear.app/stream/issue/IOS-321

🎯 Goal

We introduced a new approach to git hooks on Feeds and fixed linters' issues. The goal of this PR is to align this across all iOS repos.

🏄‍♂️ Local support

To update git hooks locally, run:

bundle install
bundle exec lefthook install

If you use Git GUI (e.g.: Fork), you have to let the GUI know about zsh PATH explicitly:

Summary by CodeRabbit

• Chores

  • Switched to Lefthook for managing Git hooks and automated code formatting in pre-commit.
  • Updated workflow automation to use Fastlane for Swift code formatting and linting.
  • Added Lefthook gem and configuration.
  • Removed custom scripts and manual Git hook setup in favor of Lefthook.
  • Removed SwiftLint build phases from the Xcode project.

• Style

  • Improved code formatting and whitespace in several files.
  • Added and adjusted SwiftLint directives for specific functions to manage linting rules.

• Documentation

  • No user-facing documentation changes.

[github-actions]

	1 Warning
⚠️	Big PR

	1 Message
📖	There seems to be app changes but CHANGELOG wasn't modified. Please include an entry if the PR includes user-facing changes. You can find it at CHANGELOG.md.

Generated by 🚫 Danger

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
StreamChatSwiftUI	9.12 MB	9.12 MB	0 KB	🟢

[sonarqubecloud]

Quality Gate failed

Failed conditions
55.9% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud