Fix GCalManager test
These patches sets the proper environment to rn GCalManager test. The first one takes advantage of the configurable tags which can be used along meson's
configure_file and creates the schema in the build directory.
The second one, compiles the schema to be ready for the GCalManager test and sets the environment variables necessary for the test to find them.
However, although this all must be done, the test still doesn't work due to an error:
--- command --- G_TEST_SRCDIR='/gnome-calendar/tests' G_TEST_BUILDDIR='/gnome-calendar/_build/tests' GSETTINGS_SCHEMA_DIR='/gnome-calendar/_build/data' GSETTINGS_BACKEND='memory' MALLOC_CHECK_='2' /gnome-calendar/_build/tests/test-manager --- stdout --- /manager/new: --- stderr --- (/gnome-calendar/_build/tests/test-manager:30472): GLib-CRITICAL **: 10:09:35.324: g_hash_table_destroy: assertion 'hash_table != NULL' failed -------
The original duplicated issue is at #189 (closed).