Improve human-readability of app_function execute-app-function output

This change introduces a --brief flag to the 'execute-app-function'
shell command. When present, the output format is more concise.

Ex: adb shell cmd app_function execute-app-function --package com.android.settings --function getUncategorizedDeviceState --parameters {} --brief

Current json format: https://paste.googleplex.com/4876070914097152

Using the --brief parameter (yaml output): https://paste.googleplex.com/4656018331795456

Bug: 432719775
Test: atest & Manually tested the new shell command functionality.
Flag: EXEMPT Tooling change for shell command output.
Change-Id: I4bcecdf70f84de8d640c9849465179add22f2477