fix: alarm and event mapping

[wilbersl]

The current alarm and event mapper doesn't correctly map type and severity, i changed it to work with thinedge standard.

TYPE keyword was missing in the topic templates
severity needs to be in the payload in lowercase

Thinedge Doc
Event
Alarm

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
16	0	0	16	100	35.322981s

Passed Tests

Name	⏱️ Duration	Suite
Device should support the operation c8y_ModbusConfiguration	0.148 s	Device
Set values via c8y_ModbusConfiguration Operation	2.410 s	Operation
Poll rate and transmit rate should be updated for the Device	0.242 s	Operation
Poll rate and transmit rate should be updated on the Device	2.391 s	Operation
Device should support the operation c8y_ModbusDevice	0.127 s	Device
Device should support the operation c8y_SerialConfiguration	0.128 s	Device
Device should have installed software tedge-modbus-plugin	0.141 s	Debian
Service should be active	2.398 s	Debian
ReInstall Modbus Plugin	25.606 s	Debian
Device should have the fragment c8y_ModbusConfiguration	0.254 s	Device
ChildDevice TestCase1 should be created	0.244 s	Device
ChildDevice TestCase1 should have the fragment c8y_ModbusDevice	0.609 s	Device
Service tedge-modbus-plugin should be enabled	0.127 s	Device
ChildDevice TestCase1 should have a Test.Int16 Measurement	0.249 s	Telemetry
ChildDevice TestCase1 should have a Test.Float32 Measurement	0.249 s	Telemetry
ChildDevice TestCase1 should have Alarms of type TestAlarm on Coil Value 1	0.001 s	Telemetry

[reubenmiller]

Approved. Thanks again for the nice PR and fixing the gaps in the plugin