fix(zigbee): Add default destructor to Window Covering and fix initialization of tm struct

[P-R-O-C-H-Y]

Description of Change

This PR add a quick fix that adds a default empty destructor + fixing a warning of uninitialized members of tm structure in addTimeCluster(); method

Tests scenarios

Compiled without any errors and warnings

Related links

[github-actions]

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[github-actions]

Memory usage test (comparing PR against master branch)

The table below shows the summary of memory usage change (decrease - increase) in bytes and percentage for each target.

Memory	FLASH [bytes]		FLASH [%]		RAM [bytes]		RAM [%]
Target	DEC	INC	DEC	INC	DEC	INC	DEC	INC
ESP32C6	0	0	0.00	0.00	0	0	0.00	0.00
ESP32H2	0	0	0.00	0.00	0	0	0.00	0.00

Click to expand the detailed deltas report [usage change in BYTES]

Target	ESP32C6		ESP32H2
Example	FLASH	RAM	FLASH	RAM
Zigbee/examples/Zigbee_CarbonDioxide_Sensor	0	0	0	0
Zigbee/examples/Zigbee_Color_Dimmable_Light	0	0	0	0
Zigbee/examples/Zigbee_Color_Dimmer_Switch	0	0	0	0
Zigbee/examples/Zigbee_Contact_Switch	0	0	0	0
Zigbee/examples/Zigbee_Dimmable_Light	0	0	0	0
Zigbee/examples/Zigbee_Occupancy_Sensor	0	0	0	0
Zigbee/examples/Zigbee_On_Off_Light	0	0	0	0
Zigbee/examples/Zigbee_On_Off_Switch	0	0	0	0
Zigbee/examples/Zigbee_Pressure_Flow_Sensor	0	0	0	0
Zigbee/examples/Zigbee_Scan_Networks	0	0	0	0
Zigbee/examples/Zigbee_Temp_Hum_Sensor_Sleepy	0	0	0	0
Zigbee/examples/Zigbee_Temperature_Sensor	0	0	0	0
Zigbee/examples/Zigbee_Thermostat	0	0	0	0
Zigbee/examples/Zigbee_Window_Covering	0	0	0	0

[github-actions]

Test Results

 62 files   62 suites   5m 39s ⏱️
 21 tests  21 ✅ 0 💤 0 ❌
153 runs  153 ✅ 0 💤 0 ❌

Results for commit 3655d54.