Set organization ID in session

What does this MR do and why?

Sets the organization ID in the session and subsequently retrieves the Organization ID from the session when present. This also unifies organization setting behavior between ApplicationController and those few controllers which fallback to the BaseActionController (like OAuth).

References

#548320 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

See comment - !194651 (comment 2625119409)

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