libsysprof-gtk: add SysprofMarkTable

This is a raw view of the marks in a session which should help for just
finding the information you care about when the visual model is too
cumbersome or lacks searching capabilities.

src/libsysprof-gtk/tests/meson.build

@@ -13,6 +13,7 @@ libsysprof_gtk_testsuite_c_args = [
 
 libsysprof_gtk_testsuite = {
   'test-callgraph' : {'skip': true},
+  'test-mark-table' : {'skip': true},
 }
 
 libsysprof_gtk_testsuite_deps = [