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_ivc.mak b/src/Make_ivc.mak
index 27b2c33..08bd874 100644
--- a/src/Make_ivc.mak
+++ b/src/Make_ivc.mak
@@ -217,6 +217,7 @@
 	"$(INTDIR)/charset.obj" \
 	"$(INTDIR)/crypt.obj" \
 	"$(INTDIR)/crypt_zip.obj" \
+	"$(INTDIR)/debugger.obj" \
 	"$(INTDIR)/dict.obj" \
 	"$(INTDIR)/diff.obj" \
 	"$(INTDIR)/digraph.obj" \
@@ -369,6 +370,10 @@
 # End Source File
 # Begin Source File
 
+SOURCE=.\debugger.c
+# End Source File
+# Begin Source File
+
 SOURCE=.\dict.c
 # End Source File
 # Begin Source File