QA Page Objects updated with new Vue files

What does this MR do?

Step 1 of https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/492. As part of refactoring snippets view, we are moving from Haml to Vue file format and QA page objects/selectors need to be updated accordingly.

In this MR I am adding new Vue references. Once snippets_vue and snippets_edit_vue feature flags are enabled by default, I will remove Haml duplicates. Keeping both for now will allow tests to run successfully in all environments, irrespective of feature flag status.

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