Address the Smartspace UI templates APIs review comments.

This is a manual cherrypick for ag/16945230 to resolve its downstream merge conflict.

- Add JavaDocs for all methods in SubItemLoggingInfo;
- Add packageName field to SubItemLoggingInfo;
- Add BaseTemplateCard.SubItemInfo to warp a subitem's related info;
- Override Object.toString for Smartspace Text.

Fixes: 220129097
Test: atest CtsSmartspaceServiceTestCases
Change-Id: I459c9a229d05d328833de1b9264b4cf64b2b5813