Fix kotlin nullable errors in Settings

Fix kotlin nullable errors that were exposed by setting the retention
of android.annotation.NonNull and android.annotation.Nullable to
class retention.

Bug: 294110802
Test: builds
Change-Id: I6aa0516fa4f6443b6d4dff873baf3b08ff9189f0

src/com/android/settings/spa/app/appinfo/AppButtons.kt

@@ -45,7 +45,7 @@ private class AppButtonsPresenter(private val packageInfoPresenter: PackageInfoP
     @Composable
     fun getActionButtons() =
         packageInfoPresenter.flow.collectAsStateWithLifecycle(initialValue = null).value?.let {
-            getActionButtons(it.applicationInfo)
+            getActionButtons(checkNotNull(it.applicationInfo))
         } ?: emptyList()
 
     @Composable

src/com/android/settings/spa/app/appinfo/AppInfoSettings.kt

@@ -118,7 +118,7 @@ object AppInfoSettingsProvider : SettingsPageProvider {
 private fun AppInfoSettings(packageInfoPresenter: PackageInfoPresenter) {
     LifecycleEffect(onStart = { packageInfoPresenter.reloadPackageInfo() })
     val packageInfo = packageInfoPresenter.flow.collectAsStateWithLifecycle().value ?: return
-    val app = packageInfo.applicationInfo
+    val app = checkNotNull(packageInfo.applicationInfo)
     RegularScaffold(
         title = stringResource(R.string.application_info_label),
         actions = {

src/com/android/settings/spa/app/appinfo/ClonePageAppButtons.kt

@@ -41,7 +41,7 @@ private class CloneAppButtonsPresenter(private val packageInfoPresenter: Package
     @Composable
     fun getActionButtons() =
         packageInfoPresenter.flow.collectAsStateWithLifecycle(initialValue = null).value?.let {
-            getActionButtons(it.applicationInfo)
+            getActionButtons(checkNotNull(it.applicationInfo))
         } ?: emptyList()
 
     @Composable

src/com/android/settings/spa/app/appinfo/PackageInfoPresenter.kt

@@ -77,7 +77,7 @@ class PackageInfoPresenter(
         DisposableBroadcastReceiverAsUser(intentFilter, userHandle) { intent ->
             if (packageName == intent.data?.schemeSpecificPart) {
                 val packageInfo = flow.value
-                if (packageInfo != null && packageInfo.applicationInfo.isSystemApp) {
+                if (packageInfo != null && packageInfo.applicationInfo?.isSystemApp == true) {
                     // System app still exists after uninstalling the updates, refresh the page.
                     reloadPackageInfo()
                 } else {