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/Filelist b/Filelist
index 1e18c67..fc6374b 100644
--- a/Filelist
+++ b/Filelist
@@ -23,6 +23,7 @@
 		src/charset.c \
 		src/crypt.c \
 		src/crypt_zip.c \
+		src/debugger.c \
 		src/dict.c \
 		src/diff.c \
 		src/digraph.c \
@@ -156,6 +157,7 @@
 		src/proto/charset.pro \
 		src/proto/crypt.pro \
 		src/proto/crypt_zip.pro \
+		src/proto/debugger.pro \
 		src/proto/dict.pro \
 		src/proto/diff.pro \
 		src/proto/digraph.pro \