Add support for temporary views by having Database#create_view accept a :temp option.
Added integration test for creating temporary views.
Add Database#supports_create_or_replace_view? private method

This will be used later after some refactoring.  H2 also
appears to support the syntax, but does not appear to work
correctly when using it, so it is not marked as supported there.
Emulate Database#create_or_replace_view if not supported directly

Refactor the existing code to make it easier to override in the
adapters.  Remove core support for temporary views, since only
PostgreSQL and SQLite support them.
Add support for temporary views on SQLite and PostgreSQL via the :temp option to create_view

These are adapter-specific options, so add adapter tests for them.
do/postgres appears not to like the added spec, causing later
freezing, so skip that spec on do/postgres.
Make create_view with a dataset work with the pg_auto_parameterize extension

Automatic parameterization should be turned off, since the query is
not executed like a normal query.