Create two new classes to deal with workloads for which we want to
collect frame metrics/jank percentages.
ApkUiautoJankTestWorkload inherits from ApkUiautoWorkload and instantiates
a UiAutomatorJankTestGUI gui member.
UiAutomatorJankTestGUI (inherits from UiAutomatorGUI) handles most of the
new logic for jank tests, including using a regular expression to parse the
final output.