RDKEMW-9745 : btMgrBus crash with function BtrCore_BTGetPairedDeviceinfo

[tharun-kumarv]

RDKEMW-9745 : btMgrBus crash with function BtrCore_BTGetPairedDeviceinfo
Reason for change: Add defensive NULL check for interface handle in DBus message creation
Priority: P1

Test Procedure: Follow the steps provided in description.
Risks:Low

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