What does this PR do?

Assign new error code JSE00001 to validation errors raised when data streams define dynamic mappings
with path_match in data stream manifests.

Why is it important?

Since Package Spec v3, it is mandatory to use field files to define fields that can be defined there. This
is the case of dynamic fields with path_match.
We have found that packages using these mappings and dynamic: "runtime" cannot ingest documents
with the error Missing intermediate object labels, likely caused because the parent object doesn't exist
in the mapping.
We should probably make Fleet to create these intermediate objects.
In the meantime, JSE00001 may offer a escape hatch for packages needing this, like in the test package
added in this PR.

After this change, packages with this issue, can add a validation.yml file at the root of the package with
the following content to ignore this error:

errors:
  exclude_checks:
    - JSE00001 # Data stream defines a dynamic mapping in manifest that should be defined in field files.

Checklist

• I have added test packages to test/packages that prove my change is effective.
• I have added an entry in spec/changelog.yml.

Related issues

• This issue blocks apmpackage: use package spec v3 apm-server#11822