### Overview
Some Executors, currently a subset of the local Executors, run in a single threaded fashion and have certain limitations and requirements, many of which are hardcoded. To add a new single threaded Executor would require changes to core Airflow code.
Note: This coupling often shows up with SQLite compatibility checks since it does not support multiple connections.
### Examples
- **2a**) SQLite check done in configuration.py: https://github.com/apache/airflow/blob/26f94c5370587f73ebd935cecf208c6a36bdf9b6/airflow/configuration.py#L412-L419
- **2b**) When running in standalone mode SQLite compatibility is checked: https://github.com/apache/airflow/blob/26f94c5370587f73ebd935cecf208c6a36bdf9b6/airflow/cli/commands/standalone_command.py#L160-L165
- **2c**) Sensors in `poke` mode can block execution of DAGs when running with single process Executors, currently hardcoded to DebugExecutor (although should also include SequentialExecutor): https://github.com/apache/airflow/blob/27e2101f6ee5567b2843cbccf1dca0b0e7c96186/airflow/sensors/base.py#L243
### Proposal
A static method or attribute on the Executor class which can be checked by core code.

There is a precedent already set with the `supports_ad_hoc_ti_run` attribute, see:
https://github.com/apache/airflow/blob/fb741fd87254e235f99d7d67e558dafad601f253/airflow/executors/kubernetes_executor.py#L435 https://github.com/apache/airflow/blob/26f94c5370587f73ebd935cecf208c6a36bdf9b6/airflow/www/views.py#L1735-L1737
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from __future__ import annotations
from datetime import timedelta
from unittest.mock import Mock, patch
import pytest
import time_machine
from airflow.exceptions import AirflowException, AirflowRescheduleException, AirflowSensorTimeout
from airflow.models import TaskReschedule
from airflow.models.xcom import XCom
from airflow.operators.empty import EmptyOperator
from airflow.sensors.base import BaseSensorOperator, PokeReturnValue, poke_mode_only
from airflow.ti_deps.deps.ready_to_reschedule import ReadyToRescheduleDep
from airflow.utils import timezone
from airflow.utils.context import Context
from airflow.utils.state import State
from airflow.utils.timezone import datetime
from tests.test_utils import db
DEFAULT_DATE = datetime(2015, 1, 1)
TEST_DAG_ID = "unit_test_dag"
DUMMY_OP = "dummy_op"
SENSOR_OP = "sensor_op"
DEV_NULL = "dev/null"
class DummySensor(BaseSensorOperator):