Annotation layers are not imported/exported.

### Bug description

Hi! Since version 3.1.1 import of annotation layers of all types except AnnotationType.FORMULA stopped working.

The import has a filter_chart_annotations stub which filters out all annotation types except FORMULA.

Also if charts are used as annotation layers they are not included in the export.

### Screenshots/recordings

_No response_

### Superset version

4.1.1

### Python version

3.9

### Node version

16

### Browser

Chrome

### Additional context

_No response_

### Checklist

- [ ] I have searched Superset docs and Slack and didn't find a solution to my problem.
- [ ] I have searched the GitHub issue tracker and didn't find a similar bug report.
- [ ] I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

Start at the filter_chart_annotations stub, then trace the annotation-layer import and export paths. Reproduce the issue with non-FORMULA annotation layers and chart layers in Superset 4.1.1. Done means all annotation types import and chart annotation layers are included in export, with regression coverage in the relevant tests.

Written by the indexing model from the issue text.