Eventually will be used to store state that's included as part of
com.android.server.pm.Settings.
Also adds equality and Kotlin index operator mutation support to
SparseArray, to improve ease of use.
Exempt-From-Owner-Approval: Already approved by owners on main branch
Bug: 163565712
CTS-Coverage-Bug: 179382047
Test: none, will be tested as part of follow up change
Change-Id: Ie4eca3a99633465337758ee165e07f35c8db87c8
e803a1bd33