[testrunner] add interface to get single value from state
[testrunner] add interface to get single value from state

graphicore/fontbakery,moyogo/fontbakery,moyogo/fontbakery,googlefonts/fontbakery,googlefonts/fontbakery,googlefonts/fontbakery,graphicore/fontbakery,graphicore/fontbakery,moyogo/fontbakery