patch 8.2.2345: no focus events in a terminal

Problem:    No focus events in a terminal.
Solution:   Add the t_fd and t_fe termcap entries and implement detecting
            focus events. (Hayaki Saito, Magnus Groß, closes #7673,
            closes #609, closes #5526)
diff --git a/src/optiondefs.h b/src/optiondefs.h
index 9afa84d..6cea017 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -2957,6 +2957,8 @@
     p_term("t_EC", T_CEC)
     p_term("t_EI", T_CEI)
     p_term("t_fs", T_FS)
+    p_term("t_fd", T_FD)
+    p_term("t_fe", T_FE)
     p_term("t_GP", T_CGP)
     p_term("t_IE", T_CIE)
     p_term("t_IS", T_CIS)