Replace Geo Notice with Toast (Backend)

What does this MR do?

This is work towards an effort to replace some of our UIs "Flash Notices" with "Toast Messages" More information can be found here: #199988 (closed)

The work will be split into two MRs, one for the backend components (Ruby) => This MR and one for the frontend components (Vue) => !24407 (merged)

Important Notes

The backend re-renders when an action happens in the controllers of Geo. Thus only one Toast message will exist on the screen at a time.

GIFs

Toasted Actions on Geo/Projects

Toasted Actions on Geo/Nodes

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

cc @sunjungp