Add COMPILER_INDEX_STORE_ENABLE=NO to Xcode build arguments #37231

This issue is triggered due to an inability to pass Xcode build arguments to flutter build ios command.

Use case

Indexing in Xcode is used mostly for

• Autocomplete
• Ability to quickly jump to definition
• Get class and method help by alt clicking.

None of these are necessary to run builds in a CI environment and disabling indexing has shown significant improvement in build speeds for developers.

• https://twitter.com/steipete/status/1100404024224804871?lang=en

Proposal

To improve the performance of flutter build process in CI environment I suggest adding buildCommands.add('COMPILER_INDEX_STORE_ENABLE=NO'); line to packages/flutter_tools/lib/src/ios/mac.dart:182-284 and add this line in case if environment variable CI exists and equals to true. Moreover, I would like to also suggest adding support for any kind of additional arguments for xcodebuild command. For example, execution of flutter build ios -- FOO=BAR will end up in xcrun xcodebuild ... FOO=BAR.