Change window-clone-border and window-close style

Window-close: simplify the normal, hover and close circle by a blue, lighter blue and darker blue solid disk
Window-clone-border: use a milky, transparent white border for the hover effect of the the border

GNOME/gnome-shell!461
Status Job ID Name Coverage
  Review
passed #248656
check_commit_log

00:02:55

 
  Build
passed #248657
build

00:02:36

 
  Test
passed #248658
test

00:01:36

passed #248659
test-pot

00:00:46