Alias and deprecate AwardEmoji mutations to match our naming guidelines

What does this MR do?

This change introduces a new #mount_aliased_mutation method as a way to deprecate mutations that do not follow our mutation naming conventions in the GraphQL API Styleguide.

In this MR, the AwardEmoji mutations are renamed according to our styleguide, and the method is used to also mount the mutations as their old names and deprecate them. This limited change allows us to discuss the change in context.

The input objects and payload responses for the old deprecated mutation remain intact, so any client integrations remain working.

Screenshots

When viewing the mutation list of the branch in GraphiQL:

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