patch 8.2.2756: Vim9: blob index and slice not implemented yet

Problem:    Vim9: blob index and slice not implemented yet.
Solution:   Implement blob index and slice.
diff --git a/src/vim9.h b/src/vim9.h
index 0c8a949..c30e597 100644
--- a/src/vim9.h
+++ b/src/vim9.h
@@ -133,6 +133,8 @@
     ISN_LISTAPPEND, // append to a list, like add()
     ISN_LISTINDEX,  // [expr] list index
     ISN_LISTSLICE,  // [expr:expr] list slice
+    ISN_BLOBINDEX,  // [expr] blob index
+    ISN_BLOBSLICE,  // [expr:expr] blob slice
     ISN_ANYINDEX,   // [expr] runtime index
     ISN_ANYSLICE,   // [expr:expr] runtime slice
     ISN_SLICE,	    // drop isn_arg.number items from start of list