Add redirect for project tags page

What does this MR do?

Brings back the redirect from project /tags to /-/tags. Addresses gitlab-com/Product#1127 (comment 340525122)

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