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