Resolve "Empty states for profile page"

What does this MR do?

Adds illustrations, text, and call-to-actions to the empty states of the profile tabs.

Screenshots

Authenticated, looking at own profile

Overview	Activity	Groups	Contributed projects	Personal projects	Snippets

Authenticated, looking at another profile / Unauthenticated

Overview	Activity	Groups	Contributed projects	Personal projects	Snippets

What are the relevant issue numbers?

#28500 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #28500 (closed)