patch 8.2.0340: Vim9: function and partial types not tested

Problem:    Vim9: function and partial types not tested.
Solution:   Support more for partial, add tests.

src/vim9.h

@@ -215,6 +215,7 @@ typedef struct {
 #endif
 	channel_T	    *channel;
 	job_T		    *job;
+	partial_T	    *partial;
 	jump_T		    jump;
 	forloop_T	    forloop;
 	try_T		    try;