patch 8.2.3442: Vim9: || and && are not handled at compile time

Problem:    Vim9: || and && are not handled at compile time when possible.
Solution:   When using constants generate fewer instructions.

src/vim9.h

@@ -221,6 +221,7 @@ typedef struct {
 
 typedef enum {
     JUMP_ALWAYS,
+    JUMP_NEVER,
     JUMP_IF_FALSE,		// pop and jump if false
     JUMP_AND_KEEP_IF_TRUE,	// jump if top of stack is truthy, drop if not
     JUMP_AND_KEEP_IF_FALSE,	// jump if top of stack is falsy, drop if not