When creating a new project, the build fails with an error similar to:
"versionCode not found. Define flutter.versionCode in the local.properties file."
This puts developers in the untenable situation of having to edit a file with local paths, but being unable to check it in.
This changes the templates to default to using versionCode 1 and version "1.0" if they are not defined in the local.properties file.
Fixes#18983.
Uses the `version` property from the `pubspec.yaml` file to set the corresponding fields in the `local.properties` file respectively in the `Generated.xcconfig` file.
The `--build-name` and `--build-number` options have changed. Now they trump the `version` property from the `pubspec.yaml` file.
If the `version` property is not set and the `--build-name` and `--build-number` options are not provided, the build command will not change the `local.properties` / `Generated.xcconfig` file.
Going forward, Android support libraries are published on maven (instead of bundling them with the SDK). Many plugins depend on these. To avoid requiring plugin users to add the maven repository to their app this change adds the repository to the template for `flutter create`.
This also bumps the support-annotations dependency to 25.4.0 (which also requires the new maven repository).
