Add changed_by functionality to Alarm Control Panel component

**Describe the problem you have/What new integration you would like**
I would like to propose adding a changed_by feature to the Alarm Control Panel component in ESPHome. This functionality would allow users to track which user disarmed the alarm, similar to the ALARMO integration in Home Assistant.

**Please describe your use case for this integration and alternatives you've tried:**
Currently, the Alarm Control Panel in ESPHome does not provide a way to identify the user responsible for changing the alarm state. This feature is crucial for users who want to maintain security and accountability within their smart home systems.

**Additional context**
Add a changed_by attribute: This attribute will hold the identifier (e.g., username or user ID) of the person who disarmed or armed the alarm.

**Example Usage**

Referencing the [ESPHome Alarm Control Panel documentation](https://esphome.io/components/alarm_control_panel/template.html), here’s an example of how the new `changed_by` attribute could be implemented:

```yaml
alarm_control_panel:
- platform: template
name: Alarm Panel
codes:
- "1234" {{ user_1 }}
- "4321" {{ user_2 }}
binary_sensors:
- input: zone_1
- input: zone_2
bypass_armed_home: true
changed_by: "{{ user_id }}"
```