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_sas.mak b/src/Make_sas.mak
index 09650c3..78d6d2a 100644
--- a/src/Make_sas.mak
+++ b/src/Make_sas.mak
@@ -96,6 +96,7 @@
 	charset.c \
 	crypt.c \
 	crypt_zip.c \
+	debugger.c \
 	dict.c \
 	diff.c \
 	digraph.c \
@@ -157,6 +158,7 @@
 	charset.o \
 	crypt.o \
 	crypt_zip.o \
+	debugger.o \
 	dict.o \
 	diff.o \
 	digraph.o \
@@ -218,6 +220,7 @@
 	proto/charset.pro \
 	proto/crypt.pro \
 	proto/crypt_zip.pro \
+	proto/debugger.pro \
 	proto/dict.pro \
 	proto/diff.pro \
 	proto/digraph.pro \
@@ -340,6 +343,8 @@
 proto/crypt.pro:	crypt.c
 crypt_zip.o:		crypt_zip.c
 proto/crypt_zip.pro:	crypt_zip.c
+debugger.o:		debugger.c
+proto/debugger.pro:	debugger.c
 dict.o:			dict.c
 proto/dict.pro:		dict.c
 diff.o:			diff.c