AO3-7253 Improve work over-reporting limit

[EchoEkhi]

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Issue

https://otwarchive.atlassian.net/browse/AO3-7253

Purpose

• Refactor the abuse report over-reporting limit checks
• Add a reportable association to abuse reports for rate-limited resources
• Fix issues when compound URLs like /works/123/comments/456 prevent /work/123 from being reported
• Remove the url LIKE "%...%" linear scan lookups
• Prevent reports for items that don't exist

Deploy notes

rake db:migrate
rake After:set_reportable

Credit

EchoEkhi (He/Him)