Conversion of related Suggestion.java files in AOSP QuickSearchBox App to Kotlin

Converted several related Suggestion files to Kotlin. All warnings were resolved, -Werror flag turned on, and code was built successfully against Kotlin 1.7. Converted files were formatted using ktfmt and imports were optimized. On conversion, many variables and return types were made nullable to maintain logic implemented in Java code.

Bug: 239665416

Test: manual testing with bramble device, unit tests ran with atest QuickSearchBoxTests with result:
Summary (Test executed with 1 devices.)
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arm64-v8a QuickSearchBoxTests: Passed: 50, Failed: 0, Ignored: 0, Assumption Failed: 0,

All tests passed!

Change-Id: Iea43c949f963ce45f5d79a4ca6fd32b02681e31e
9 files changed