The appinfo-test.desktop file is set up with an Exec= path which points
to the compiled and installed appinfo-test utility. When running the
tests uninstalled, however, this might not be present, which causes
loading appinfo-test.desktop to fail.
Split appinfo-test.desktop in two: keep the existing
appinfo-test.desktop for tests which need to launch appinfo-test, and
add a new appinfo-test-static.desktop for tests which don’t launch
anything (and, for example, just inspect GAppInfo properties).
appinfo-test-static.desktop uses an Exec= line which should always be
present (`true`) so it should never fail to load.
Allow the tests using appinfo-test-static.desktop to be run uninstalled
or installed. Allow the tests using appinfo-test.desktop to be skipped
if loading appinfo-test.desktop fails, which is an indicator that the
test is running uninstalled.
Signed-off-by: Philip Withnall <withnall@endlessm.com>