Add SONOFF Dongle-LMG21 range extender fingerprint

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Type of Change

• WWST Certification Request
  • If this is your first time contributing code:
    • I have reviewed the README.md file
    • I have reviewed the CODE_OF_CONDUCT.md file
    • I have signed the CLA
  • I plan on entering a WWST Certification Request or have entered a request through the WWST Certification console at developer.smartthings.com
• Bug fix
• New feature
• Refactor

Checklist

• I have performed a self-review of my code
• I have commented my code in hard-to-understand areas
• I have verified my changes by testing with a device or have communicated a plan for testing
• I am adding new behavior, such as adding a sub-driver, and have added and run new unit tests to cover the new behavior

Description of Change

Add a fingerprint for the SONOFF Dongle-LMG21 running Zigbee router firmware to the existing zigbee-range-extender driver.

• Manufacturer: SONOFF
• Model: Dongle-LMG21
• Device label: SONOFF Zigbee Range Extender
• Device profile: range-extender

This change reuses the existing driver implementation and device profile. No Lua code, capabilities, or device profiles are changed.

Summary of Completed Tests

Manually tested with a SONOFF Dongle-LMG21 running custom-built Zigbee router firmware and a SmartThings Hub V3.

Verified in the SmartThings app that:

• The device was successfully added and displayed as SONOFF Zigbee Range Extender.
• The reported manufacturer and model were SONOFF and Dongle-LMG21, matching the new fingerprint.
• The device was using the Zigbee Range Extender driver distributed through SONOFF Router Test Channel.
• The device status showed Connected.
• The connection path showed a direct connection between the hub and the device.

The screenshots below show the assigned driver, device information, connection status, and connection path.

These checks cover device onboarding and driver association. Routing traffic for other Zigbee devices was not verified as part of these checks.

[github-actions]

Invitation URL:
https://bestow-regional.api.smartthings.com/invite/1PlYykqye3le

[github-actions]

zigbee-range-extender_coverage.xml

File	Coverage
All files	88%	❌
/home/runner/work/SmartThingsEdgeDrivers/SmartThingsEdgeDrivers/drivers/SmartThings/zigbee-range-extender/src/init.lua	76%	❌
/home/runner/work/SmartThingsEdgeDrivers/SmartThingsEdgeDrivers/drivers/SmartThings/zigbee-range-extender/src/lazy_load_subdriver.lua	57%	❌

Minimum allowed coverage is 90%

Generated by 🐒 cobertura-action against e914f25

[github-actions]

Test Results

   73 files    544 suites   0s ⏱️
3 304 tests 3 304 ✅ 0 💤 0 ❌
5 297 runs  5 297 ✅ 0 💤 0 ❌

Results for commit e914f25.

♻️ This comment has been updated with latest results.