patch 8.1.1195: Vim script debugger functionality needs cleanup

Problem:    Vim script debugger functionality needs cleanup.
Solution:   Move debugger code to a separate file.  Add more tests. (Yegappan
            Lakshmanan, closes #4285)
diff --git a/src/Make_bc5.mak b/src/Make_bc5.mak
index 1c13931..62d0397 100644
--- a/src/Make_bc5.mak
+++ b/src/Make_bc5.mak
@@ -516,6 +516,7 @@
 	$(OBJDIR)\charset.obj \
 	$(OBJDIR)\crypt.obj \
 	$(OBJDIR)\crypt_zip.obj \
+	$(OBJDIR)\debugger.obj \
 	$(OBJDIR)\dict.obj \
 	$(OBJDIR)\diff.obj \
 	$(OBJDIR)\digraph.obj \