### 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
"""
        Set success state for the event.
        :param info: Executor information for the task instance
        :param key: Unique key for the task instance
        """
        self.change_state(key, State.SUCCESS, info)
    def get_event_buffer(self, dag_ids=None) -> dict[TaskInstanceKey, EventBufferValueType]:
        """
        Return and flush the event buffer.
        In case dag_ids is specified it will only return and flush events
        for the given dag_ids. Otherwise, it returns and flushes all events.
        :param dag_ids: the dag_ids to return events for; returns all if given ``None``.
        :return: a dict of events
        """
        cleared_events: dict[TaskInstanceKey, EventBufferValueType] = {}
        if dag_ids is None:
            cleared_events = self.event_buffer
            self.event_buffer = {}
        else:
            for ti_key in list(self.event_buffer.keys()):
                if ti_key.dag_id in dag_ids:
                    cleared_events[ti_key] = self.event_buffer.pop(ti_key)
        return cleared_events
    def execute_async(