Add 🧅 Onion-Location Header to all onion services

Many Tor Project web adresses have an onion service but do not advertise it using the Onion-Location header.

Add this header to the following hosts:

• archive.torproject.org
• bridges.torproject.org
• collector2.torproject.org
• collector.torproject.org
• dist.torproject.org
• donate-api.torproject.org
• fpcentral.tbb.torproject.org (retired in #40009 (closed))
• gitweb.torproject.org
• jenkins.torproject.org (retired)
• metrics.torproject.org
• onionoo.torproject.org
• spec.torproject.org
• staging.donate-api.torproject.org
• test-api.donate.torproject.org
• test.donate-api.torproject.org
• www-staging.torproject.org