### Description

Add DagProcessor status including latest heartbeat to health endpoint similar to Triggerer status added recently. Related PRs.

https://github.com/apache/airflow/pull/31529
https://github.com/apache/airflow/pull/27755

### Use case/motivation

It helps in dag processor monitoring 

### Related issues

_No response_

### Are you willing to submit a PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

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from __future__ import annotations
from marshmallow import Schema, fields
class BaseInfoSchema(Schema):
    """Base status field for metadatabase and scheduler."""
    status = fields.String(dump_only=True)
class MetaDatabaseInfoSchema(BaseInfoSchema):
    """Schema for Metadatabase info."""
class SchedulerInfoSchema(BaseInfoSchema):
    """Schema for Scheduler info."""
    latest_scheduler_heartbeat = fields.String(dump_only=True)
class TriggererInfoSchema(BaseInfoSchema):
    """Schema for Triggerer info."""
    latest_triggerer_heartbeat = fields.String(dump_only=True)
class HealthInfoSchema(Schema):
    """Schema for the Health endpoint."""
    metadatabase = fields.Nested(MetaDatabaseInfoSchema)
    scheduler = fields.Nested(SchedulerInfoSchema)
    triggerer = fields.Nested(TriggererInfoSchema)
health_schema = HealthInfoSchema()