Add retry logic for AV defense to winOpen. Also, refactor test suite to allow the key Tcl file operations (e.g. copy and delete) to be retried.

FossilOrigin-Name: 9007586fdabed8dbcc78581ea9821cfd1f9a4c8c

test/lock5.test

@@ -24,7 +24,7 @@ if {[catch {sqlite3 db test.db -vfs unix-none} msg]} {
   return
 }
 db close
-file delete -force test.db.lock
+forcedelete test.db.lock
 
 ifcapable lock_proxy_pragmas {
   set ::using_proxy 0
@@ -100,7 +100,7 @@ do_test lock5-dotfile.X {
 
 #####################################################################
 
-file delete -force test.db
+forcedelete test.db
 if {[catch {sqlite3 db test.db -vfs unix-flock} msg]} {
   finish_test
   return