Replace existing cluster FSM with global GitLab FSM

What does this MR do?

Replaces an existing FSM with the RFC#65 FSM implementation.

Notably, the base implementation is a strict finite state machine without any additional behavior implementations.

So, the "exit context" implemented here is shifted around to match against the new FSM implementation.
Basically, where the additional arbitrary context was part of the state machine before, it's now a corollary function that is called to return the additional context.

Before, the state machine had both a target state and a set of side effects for a given state + transition combination.
In the update, a given state + transition only maps to another state. The associated side effects are moved out to another mapping that associates the correct new context (like { someKey: 'updatedValue' }) to the relevant state + transition (like someState:someTransition).

This new function call to get the exit context directly replaces the previous .effects property of the state machine.

Screenshots

N/A, all ~"feature::maintenance"

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team