Fixed: Do not stop the app if UncaughtExceptionHandler implemented by CrashHandler receives an exception on a non main thread

Rename function that should be used by main thread of apps to `setDefaultCrashHandler()`.

Functions for other threads will be added in a later commit.

app/src/main/java/com/termux/app/TermuxApplication.java

@@ -20,7 +20,7 @@ public class TermuxApplication extends Application {
         Context context = getApplicationContext();
 
         // Set crash handler for the app
-        TermuxCrashUtils.setCrashHandler(this);
+        TermuxCrashUtils.setDefaultCrashHandler(this);
 
         // Set log config for the app
         setLogConfig(context);