java_gen: correctly handle of_action 64-bit alignment

of_action is different from oxm in that it is 64 bit aligned,
but the alignment is contained in the length field.

Added optional parameter "length_includes_align" to the input files
to handle this situation.
java_gen: support glob based test_data files

enables us to have more than on unit test per class.

Additional tests follow the pattern:
${class_name}__${suffix}.data
test_data: add java stanzas to action tests

and rename them to follow the glob conventions for java_gen