Make sure sendresult after association was created

Add a new method to send activity result in
CompanionDeviceDiscoveryService and make sure
CDMService to call it before addAssociation.

Bug: 203418937
Test: Test: CTS Verifier test: Companion Device Service Test, Companion Device
Test and cts test: atest CtsOsTestCases:android.os.cts.CompanionDeviceManagerTest
Change-Id: Ied7d705934418869287a8be6cd44abe3b806db00
Merged-In: Ied7d705934418869287a8be6cd44abe3b806db00