### Description


We need to access the time at which a given DAG was parsed last.

Airflow Version : 2.2.2 and above.

### Use case/motivation

End users want to run a given DAG post applying the changes they have done on them. This would mean that the DAG should be parsed post the edits done to it. Right now the last parsed time is available by accessing the airflow database only. Querying the database directly is not the best solution to the problem. Ideally airflow should be exposing APIs that end users can consume that can help provide the last parsed time for a given DAG.

### Related issues

Not Aware.

### Are you willing to submit a PR?

- [ ] 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)

if not os.path.isdir(arg):
            parser.error(f"The directory '{arg}' does not exist!")
        return arg
def positive_int(*, allow_zero):
    """Define a positive int type for an argument."""
    def _check(value):
        try:
            value = int(value)
            if allow_zero and value == 0:
                return value
            if value > 0:
                return value
        except ValueError:
            pass
        raise argparse.ArgumentTypeError(f"invalid positive int value: '{value}'")
    return _check
def string_list_type(val):
    """Parses comma-separated list and returns list of string (strips whitespace)."""
    return [x.strip() for x in val.split(",")]
def string_lower_type(val):
    """Lowers arg."""
    if not val:
        return
    return val.strip().lower()
ARG_DAG_ID = Arg(("dag_id",), help="The id of the dag")
ARG_TASK_ID = Arg(("task_id",), help="The id of the task")
ARG_EXECUTION_DATE = Arg(("execution_date",), help="The execution date of the DAG", type=parsedate)
ARG_EXECUTION_DATE_OPTIONAL = Arg(
    ("execution_date",), nargs="?", help="The execution date of the DAG (optional)", type=parsedate
)