Add Algolia as a configurable search option (Initial implementation)

[benhalpern]

Is this feature related to a problem? Please describe.

Large Forems (like DEV) can benefit from more advanced search options that one is default available in Postgres — though Postgres should remain the default so functionality works out of the box.

Describe the solution you’d like

• Make all current searchable models (article, user, organization, tags, comments, podcasts) have all relevant fields indexed by Algolia.
• Adjust frontend to search directly from the Algolia endpoint when enabled.
• Add admin configuration to display "powered by Algolia" messaging (specific for DEV since we are working directly with them, does not have to be turned on)

Definition of Done

• Add ENV variable for all Algolia functionality. Only use when turned on.
• Add backend indexing on changes
• Send traffic straight to Algolia endpoint from client
• Add admin configuration for "Powered by Algolia" message

Additional Context

• Algolia has a 10k default record size limit. There are workarounds, but V1 we should just cut off content as that should suffice.
• Once this is in we can add more custom functionality, but step 1 is the integration.

[github-actions]

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