[2314] Add setup method in session service

[BobrImperator]

closes #2314
closes #1854, and closes #2279

• Adds #setup method for session service
• Adds useSessionSetupMethod 'run time' configuration for setup-session-restoration intiializer to return early
• Adds deprecation when initializer is being used indicating the migration to session#setup instead.
• Documents how to use the #setup method along with the configuration options guides/upgrate-to-v4.md.

I was able to successfully confirm this working in my private project which conveniently is written in typescript #1854, #2279.

[marcoow]

This is great! I think we should do a few more things though:

• in all public methods of the session service, we should assert that setup has been called so that people that forget to do it get better feedback
• use this new option in the test app
• strip the initializer from the app build completely if the new option is set

[marcoow]

👍

[bertdeblock]

This PR also introduces 3 new deprecations (aside from the intended setup method one):

`import { deprecate } from '@ember/application/deprecations';` has been deprecated, please update to `import { deprecate } from '@ember/debug';`

When calling `deprecate` you must provide `for` in options. Missing options.for in "ember-simple-auth.initializer.setup-session-restoration" deprecation

When calling `deprecate` you must provide `since` in options. Missing options.since in "ember-simple-auth.initializer.setup-session-restoration" deprecation

[steveszc]

Should there be a link to the upgrade guide in the README?
Right now the README does not mention anything about the session's setup method...

[BobrImperator]

@steveszc Thanks, will try to work out better documentation for this