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/shared7.test

@@ -35,7 +35,7 @@ do_test shared7-1.2 {
 } {1 {database is already attached}}
 
 do_test shared7-1.3 {
-  file delete -force test2.db test2.db-journal
+  forcedelete test2.db test2.db-journal
   db eval {
     ATTACH 'test2.db' AS test2;
     CREATE TABLE test2.t2(y);