Make FilterPropertyStructSharded smarter

FilterPropertyStructSharded was just sharding the top level
properties into groups of 10.  For nested property structs
this can be insufficient - there could be a single top level
property with many properties below it.

Take a maximum name size, and track the size used by parent
structs to determine when sharding a nested struct is necessary.

Bug: 146234651
Test: filter_test.go
Change-Id: I5b5ed11ea27a0325b2fd6c2c3fb427ea1e2af0c2