Initial Googletest test for Dumpstate server

This is a very simple test simply verifying that a command can be run
by the ServiceDescriptor API & return the expected output. This CL
however does all the plumbing required to bring Googletest into
the trout AGL build infrastructure & to verify that one can indeed
write and run testcases in the trout host environment

Bug: 158844592
Test: run dumpstate_tests on dev board
Change-Id: I0868ee676a0b14647db4990547751ac763bca7c7