Refactor the service desk list to use Vue

What does this MR do?

This merge request should have been broken down into smaller MRs but ended up becoming a large MR.

• Add the logic to render the issues list using the Vue component issuables_list_app.vue in the Service Desk page.

• Spin off some code from _service_desk_info_content.html.haml into _service_desk_empty_state.html.haml.

  Previously _service_desk_info_content.html.haml displayed both

  • the "empty state" message that is shown to the user when the list is either unavailable or empty
  • and the "informational" message that always appears above the list (this only happens in the Service Desk page).

  This was necessary because issuables_list_app.vue was built to display the empty state message through gl-empty-states component and I didn't find it semantic to display the information message using gl-empty-states.

• Modify the props for issuables_list_app.vue.

  issuables_list_app.vue used to accept createIssuePath and emptySvgPath as props but these props merged into one emptyStateMeta prop. This change was made so that issuables_list_app.vue can accept the necessary data for displaying the empty state messages that are a bit more complex in the Service Desk.

Screenshots

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

Issue #233725 (closed)