Support configuration for skip checking of schema existence before switching

[rpbaltazar]

Steps to reproduce

Using postgresql, when running Apartment::Tenant.switch, before switching it check for the schema existence. In some cases, when there is a fair amount of load in the database, this can have an impact since it is yet another query being done.

Expected behavior

I think we should support a configuration that allows the apartment users to skip the schema existence and let them handle the errors on their end however they want.

Actual behavior

Currently there is no way to support this unless we monkeypatch the postgresql adapter in order to achieve it.

System configuration

• Database: (Tell us what database and its version you use.)

postgresql - 12.0

• Apartment version: 2.3.0

• Apartment config (in config/initializers/apartment.rb or so):

  • use_schemas: true

• Rails (or ActiveRecord) version: 6.0.2.1

• Ruby version: 2.6

[rpbaltazar]

As part of the migration running, it should be fine to check for the schema existence. Maybe show a warning message informing the user that there are schemas being referenced that do not exist in the database and show a proposed solution:
Either remove the record that references that non existent schema or create the schema.