BREAKING CHANGE:
Removed several deprecated APIs:
- EngineHost `listSchematics` has been removed in favour of `listSchematicNames`.
- `FileSystemSink` - Use the new virtualFs.Host classes from `@angular-devkit/core`.
- `optimize` function has been remove as trees are automaticlly optimized.
- `DryRunSink` deprecated constructor that allowed to provide a directory path has been removed. Provide a `virtualFs.Host` instead.
Schematics context now have an (optional) analytics field that, if set,
should be used to report usage. This can be set even in some cases where
analytics is disabled (to a noop analytics).
