Update avatar_helper to accept GraphQL id

What does this MR do?

Update avatar_helper to accept GraphQL id

• with the company being GraphQL-first, there is a rise of using the GraphQL ids, which is formatted differently than the database ids (e.g. gid://gitlab/Project/8 vs 8)
• update the avatar_helper to accept a GraphQL id
• update the identicon component to accept GraphQL ids
• add tests

Screenshots

Two usages of the affected method

• app/assets/javascripts/search_autocomplete.js
• app/assets/javascripts/vue_shared/components/identicon.vue

Four usages of the affected component

• app/assets/javascripts/clusters/components/application_row.vue
• app/assets/javascripts/frequent_items/components/frequent_items_list_item.vue
• app/assets/javascripts/groups/components/group_item.vue
• app/assets/javascripts/vue_shared/components/project_avatar/default.vue

Before (staging)

search_autocomplete

identicon in app/assets/javascripts/vue_shared/components/project_avatar/default.vue using the database ids

After (local)

usage of avatar_helper with GraphQL (it looks the same! 🎉 )

search_autocomplete

identicon in app/assets/javascripts/vue_shared/components/project_avatar/default.vue using GraphQL ids

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

Related to #214583 (closed)