Tell Meson which tests produce TAP output

GLib, and the Python tests with the taptestrunner.py we copy-pasta, emit
output that conforms to Test Anything Protocol
<https://testanything.org/>, allowing the runner to know the number of
subtests and which of them passed.

With this information, Meson can produce this information to the console
when you run `meson test`:

 1/20 eos-updater:libeos-updater-util / avahi-service-file    OK   0.04s   4 subtests passed
 2/20 eos-updater:libeos-updater-util / ostree-util           OK   0.03s   1 subtests passed

I believe it also includes this information in the JUnit XML it emits
and that our Jenkins consumes.

https://phabricator.endlessm.com/T35247

libeos-updater-flatpak-installer/tests/meson.build

@@ -65,5 +65,6 @@ foreach test_name, extra_args : test_programs
     env: envs,
     suite: suite,
     timeout: extra_args.get('slow', false) ? 360 : 60,
+    protocol: 'tap',
   )
 endforeach

libeos-updater-util/tests/meson.build

@@ -66,5 +66,5 @@ foreach test_name, extra_args : test_programs
   )
 
   suite = ['libeos-updater-util'] + extra_args.get('suite', [])
-  test(test_name, exe, env : envs, suite : suite)
+  test(test_name, exe, env : envs, suite : suite, protocol : 'tap')
 endforeach

tests/meson.build

@@ -115,6 +115,7 @@ foreach test_name, extra_args : test_programs
     suite: ['eos-updater'] + extra_args.get('suite', []),
     timeout: extra_args.get('slow', false) ? 600 : 60,
     is_parallel: extra_args.get('parallel', true),
+    protocol: 'tap',
   )
 endforeach
 
@@ -160,6 +161,7 @@ foreach test_name, extra_args : python_tests
       args: main,
       env: envs,
       suite: ['eos-updater'] + extra_args.get('suite', []),
+      protocol: 'tap',
     )
   endif
 endforeach