* Add parser support for Flow declare fields
* Add generator test
* Add "allowDeclareFields" option to flow-strip-types
* Add test
* Update error messages
* More tests
| Q | A <!--(Can use an emoji 👍) -->
| ------------------------ | ---
| Fixed Issues? |
| Patch: Bug Fix? |
| Major: Breaking Change? |
| Minor: New Feature? |
| Tests Added + Pass? | Yes
| Documentation PR | <!-- If so, add `[skip ci]` to your commit message to skip CI -->
| Any Dependency Changes? |
| License | MIT
The `all` option landed in https://github.com/babel/babel/pull/7934/files#diff-3a8233bcd2766d2c7d87f23f944f7726R3 but it is only exposed from the plugin, not the preset, so this exposes it there too since the flow preset is what we want people to use.
