A few inline autofill API tweaks.

* add isPinned() to InlineSuggestionInfo so IME can choose to pin the suggestion
* allow augmented autofill service to set inline actions in the response
* non-api change: pull the autofill hints from the Slice in the InlinePresentation

Test: m -j; atest InlinePresentationTest, atest CtsInputMethodTestCases:InlineSuggestionInfoTest CtsInputMethodTestCases:InlineSuggestionTest
Bug: 137800469

Change-Id: I63b6b843ef056df18c317299e617b8fe21907374