[flutter_tools] Lazily initialize AppleContext dependencies via builder closures - #191992

Description

This PR updates AppleContext to initialize its 8 Apple-specific dependencies via lazy builder closures memoized in late final fields, and defers construction of XCDevice, IOSSimulatorUtils, and CocoaPodsValidator out of ToolDependencies.bootstrap and generateCommands.

Why this is needed now

Previously, AppleContext held 8 eager fields (cocoaPods, cocoapodsValidator, iosSimulatorUtils, iosWorkflow, plistParser, xcdevice, xcode, xcodeProjectInterpreter), and ToolDependencies.bootstrap and runner.run instantiated all 8 unconditionally on every host operating system (including Linux and Windows) and on commands that do not target Apple devices. In particular, XCDevice eagerly constructed IMobileDevice, IOSDeploy, IOSCoreDeviceControl, XcodeDebug, and registered a shutdown hook, and IOSSimulatorUtils eagerly constructed SimControl.

Note that Xcode, XcodeProjectInterpreter, CocoaPods, IOSWorkflow, and PlistParser are still accessed during startup (AttachCommand/CleanCommand/DaemonCommand/BuildCommand in generateCommands, EmulatorManager, and FlutterProjectFactory), though their constructors only assign fields and do not spawn processes.

Changes

• Updated AppleContext to accept builder closures (cocoaPodsBuilder, cocoapodsValidatorBuilder, iosSimulatorUtilsBuilder, iosWorkflowBuilder, plistParserBuilder, xcdeviceBuilder, xcodeBuilder, and xcodeProjectInterpreterBuilder) backed by late final fields for lazy evaluation and memoization.
• Updated ToolDependencies.bootstrap to use late final locals for Apple dependencies and accept optional *Builder callbacks, and updated runner.dart to pass lazy builder closures for globals fallbacks.
• Updated FlutterDeviceManager to remove redundant iosSimulatorUtils, iosWorkflow, and xcDevice constructor parameters and initialize deviceDiscoverers lazily via late final from _appleContext.

Related Issues

Part of #47161 (flutter_tools modular dependency injection migration).

Tests

• Updated packages/flutter_tools/test/general.shard/context/dependency_injection_test.dart to verify AppleContext lazily evaluates and memoizes all 8 dependencies and ToolDependencies.bootstrap defers XCDevice construction until first access.
• Updated packages/flutter_tools/test/general.shard/runner/runner_test.dart to verify CocoaPodsValidator, IOSSimulatorUtils, and XCDevice are not eagerly evaluated during bootstrap or generateCommands.