Fix memory leak in ArraysTestCase unit test.

Clear the items in PTR array explicitly, this is not done by the array itself.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76906 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix inserting an element of wxArrayString itself back into it.

Do the insertion/addition before deallocating the old memory to allow things
like array.Add(array[0]) to work correctly.

Closes #2290.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76907 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775