Generate a new assistStructure for secondary fill request

When the user changes focus from a view to a secondary view type, then
generate a new assistStructure. When the user changes focus, the user
could have moved on to a different fragment and require a new
assistStructure. Create a new fill request with the new assistStructure
and request to the secondary provider handler.

And when the updateLocked is called for the secondary view, handle the
secondary provider logic and return early. The session should process
logic for one provider at a time.

Bug: 315343520
Test: atest CtsAutoFillServiceTestCases
Change-Id: Ie825668ecdc3e250d81789354cc63abb51940bfe