Prototype XML view compiler

Prototype XML view compiler

This is an initial step towards a tool for pre-compiling layout XML files.  It
accepts an XML file and produces a Java language class called CompiledView with
a static method, inflate. Calling CompiledView.inflate should then return a view
object that is equivalent to calling LayoutInflater.inflate on the same
resource.

There are still several important limitations, but this works well enough to do
some experimentation. The limitations include:
* Currently only one layout can be compiled at a time.
* `merge` and `include` nodes are not supported.
* View compilation is a manual process that requires code changes in the
  application.
* The tests in this CL do not yet exercise any interesting behavior.

Bug: 111895153
Change-Id: I3e6880b08c52087d24ae7486495bd7fa282f4ff7