Access2Base - solve compatibility issues

1) AOO <> LO
"Append" is a reserved word in AOO Basic, not in LO
=> Append method replaced with Add

2) Windows <> Linux
ActiveConnection not ready under Windows for standalone forms when database is (user/password) protected
=> Connection may be postponed to first use of form

Change-Id: I8ba409191ba2a2a4c057480ec3287d7d48262073
Reviewed-on: https://gerrit.libreoffice.org/9372
Reviewed-by: Lionel Elie Mamane <lionel@mamane.lu>
Tested-by: Lionel Elie Mamane <lionel@mamane.lu>