patch 8.2.2162: Vim9: Cannot load or store autoload variables

Problem:    Vim9: Cannot load or store autoload variables.
Solution:   Add ISN_LOADAUTO and ISN_STOREAUTO. (closes #7485)
diff --git a/src/vim9.h b/src/vim9.h
index 26b2080..26307c2 100644
--- a/src/vim9.h
+++ b/src/vim9.h
@@ -24,6 +24,7 @@
     ISN_LOAD,	    // push local variable isn_arg.number
     ISN_LOADV,	    // push v: variable isn_arg.number
     ISN_LOADG,	    // push g: variable isn_arg.string
+    ISN_LOADAUTO,   // push g: autoload variable isn_arg.string
     ISN_LOADB,	    // push b: variable isn_arg.string
     ISN_LOADW,	    // push w: variable isn_arg.string
     ISN_LOADT,	    // push t: variable isn_arg.string
@@ -41,6 +42,7 @@
     ISN_STORE,	    // pop into local variable isn_arg.number
     ISN_STOREV,	    // pop into v: variable isn_arg.number
     ISN_STOREG,	    // pop into global variable isn_arg.string
+    ISN_STOREAUTO,  // pop into global autoload variable isn_arg.string
     ISN_STOREB,	    // pop into buffer-local variable isn_arg.string
     ISN_STOREW,	    // pop into window-local variable isn_arg.string
     ISN_STORET,	    // pop into tab-local variable isn_arg.string