components/dsmr/text_sensor.py: adding "equipment_id" - single line fix

### The problem

In the standard installation the "equipment id" is not propagated, but it is supported by all electricity meters.
I have several electricity meters and this helps identify them on the MQTT bus.

This can be remedied by a simple fix, tested and working.

### The solution

Suggested commit comment:
`Enable the propagation of "equipment_id" parameter.
`

Example config:
```YAML
...
text_sensor:
- platform: dsmr
equipment_id:
name: "Energy Meter ID"
...
```

```Diff
diff --git a/esphome/components/dsmr/text_sensor.py b/esphome/components/dsmr/text_sensor.py
index 202cc070..50b12e74 100644
--- a/esphome/components/dsmr/text_sensor.py
+++ b/esphome/components/dsmr/text_sensor.py
@@ -17,6 +17,7 @@ CONFIG_SCHEMA = cv.Schema(
cv.Optional("electricity_failure_log"): text_sensor.text_sensor_schema(),
cv.Optional("message_short"): text_sensor.text_sensor_schema(),
cv.Optional("message_long"): text_sensor.text_sensor_schema(),
+ cv.Optional("equipment_id"): text_sensor.text_sensor_schema(),
cv.Optional("gas_equipment_id"): text_sensor.text_sensor_schema(),
cv.Optional("thermal_equipment_id"): text_sensor.text_sensor_schema(),
cv.Optional("water_equipment_id"): text_sensor.text_sensor_schema(),
```
### Which version of ESPHome has the issue?

Version <= 2024.3.0

### What type of installation are you using?

pip

### What platform are you using?

ESP32

### Additional information

Esphome rocks!
Thank you all!