Add hereditary option to as_object_map. This automatically apply as_object_map to the values of the map when the values are "plain old objects".

This behavior is slightly naive but I think it will satisfy most people who have requested this feature.


- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry
- [x] Add / update tests
- [x] Add new / update outdated documentation

package:
  name: pkg_1_1
  version: 1.0.0
source:
  sha256: deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef
  url: https://dummy-url-that-not-exists.com/pkg_1_1-py3-none-any.whl
test:
  imports:
    - pkg_1_1

package:
  name: pkg_1_1
  version: 1.0.0
source:
  sha256: deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef
  url: https://dummy-url-that-not-exists.com/pkg_1_1-py3-none-any.whl
test:
  imports:
    - pkg_1_1
