vte3-gi: add post_load to require libraries
vte3-gi test: use setup
vte3-gi test: add property test
vte3-gi test: remove unneeded test
vte3-gi test: split test
vte3-gi test: rename test

test_set_font ->
test_font
vte3-gi test: add signal tests
vte3-gi: make private Vte::Loader methods
vte3-gi test: add Vte::Pty test