Enable Kotlin Strict API mode by default

This change opts out failing projects and fixes a few that
had only a few violations.

Test: ./gradlew assembleDebug
Change-Id: I556fcb811f12161fa57748ab82c23933a28143c8
diff --git a/paging/guava/build.gradle b/paging/guava/build.gradle
index a88b458..9c323c6 100644
--- a/paging/guava/build.gradle
+++ b/paging/guava/build.gradle
@@ -47,6 +47,7 @@
     mavenGroup = LibraryGroups.PAGING
     inceptionYear = "2019"
     description = "Android Paging Guava"
+    legacyDisableKotlinStrictApiMode = true
 }
 
 // Allow usage of Kotlin's @OptIn.