Change spinner to lazily read database stuff.

Otherwise you get into situations where Spinner will force DB accesses
super early during Application#onCreate on the main thread, which can be
bad when testing large DB migrations.

spinner/app/src/main/java/org/signal/spinnertest/MainActivity.kt

@@ -20,10 +20,10 @@ class MainActivity : AppCompatActivity() {
     Spinner.init(
       application,
       mapOf(
-        "Name" to "${Build.MODEL} (API ${Build.VERSION.SDK_INT})",
-        "Package" to packageName
+        "Name" to { "${Build.MODEL} (API ${Build.VERSION.SDK_INT})" },
+        "Package" to { packageName }
       ),
-      mapOf("main" to Spinner.DatabaseConfig(db = db)),
+      mapOf("main" to Spinner.DatabaseConfig(db = { db })),
       emptyMap()
     )
   }