Create function based indexes automatically to speed up case insensitive queries on the database

See the entire discussion on XWIKI-8691 about the need for automatically adding function based indexes (e.g. lower(DOC_FULLNAME)) for having a good performance with case insensitive queries that are currently not using any index at all.

Options:

• Use Hibernate's database mapping file when initializing a database (currently problematic, see XWIKI-8691's comments)
• Use liquibase schema manipulation during a data migration