[Android Demo App] Make android demo app responsive and improve some ux

[abhinaykukkadapu]

While trying to use demo apps for the demo found few issues and this PR contains some of them i used to unblock:

1. Make settings pane more responsive, before i had to click exactly on the corner of the dropdown and it was hard on a small screen
2. Make settings pane scrollable as the device screen i have is small the clear button wouldn't show before
3. fix llava prompt template (this is only a part of the fix), the model currently fails with error 17. I think xnnpack backend needed sine op to make llava work.

[psiddh]

We do not need a new Thread here, nor runOnUIThread. setupDataPathSelectorDialog() is already on the UI Thread, this can be as simple as

private void setupDataPathSelectorDialog() {
mDataPathTextView.setText("Loading...");

   String[] dataPathFiles =
              listLocalFile("/data/local/tmp/llama/", new String[] {".ptd"});
          runOnUiThread(
              () -> {
                mDataPathTextView.setText(
                    mDataPath != null ? getFilenameFromPath(mDataPath) : "no data path selected");
                AlertDialog.Builder dataPathBuilder = new AlertDialog.Builder(this);
                dataPathBuilder.setTitle("Select data path");

                String[] dataPathOptions = new String[dataPathFiles.length + 1];
                for (int i = 0; i < dataPathFiles.length; i++) {
                  dataPathOptions[i] = dataPathFiles[i];
                }
                dataPathOptions[dataPathOptions.length - 1] = "(unused)";

                dataPathBuilder.setSingleChoiceItems(
                    dataPathOptions,
                    -1,
                    (dialog, item) -> {
                      if (dataPathOptions[item] != "(unused)") {
                        mDataPath = dataPathOptions[item];
                        mDataPathTextView.setText(getFilenameFromPath(mDataPath));
                      } else {
                        mDataPath = null;
                        mDataPathTextView.setText(
                            getFilenameFromPath("no data path selected"));
                      }
                      mLoadModelButton.setEnabled(true);
                      dialog.dismiss();
                    });

                dataPathBuilder.create().show();

}

Can we do this to all the functions similarly ?

[psiddh]

Thanks @abhinaykukkadapu for this PR. This should help in addressing few UI issues

[abhinaykukkadapu]

@psiddh i think you are right, the non-responsiveness seems to stem from clicking the small icon at the corner, now it is still responsive. Modified in the latest patch.