Medicines: replace in-memory search with pg full text search with GIN index

[rithviknishad]

Proposed Changes

• Removed in-memory table MedibaseMedicinesTable and support for in-memory search.
• Adds GIN Index on the Medicines table (+ migration to install the Postgres extension)
• Annotates and orders with search rank (priority: generic, name, company, cims_class, contents)
• Updated API endpoint and views to reflect the changes and support for pagination.

Before: with the in-memory table (93ms ~ 128ms)

After: Search on Postgres with GIN Index and order by SearchRank (122ms ~ 170ms)

(Postgres is not on the same machine; on a Linux machine on the same local network)

Index Size (~64 MB)

Merge Checklist

• Tests added/fixed
• Update docs in /docs
• Linting Complete
• Any other necessary step

Only PR's with test cases included and passing lint and test pipelines will be reviewed

@coronasafe/care-backend-maintainers @coronasafe/care-backend-admins

[rithviknishad]

will update tests

[sainak]

Migrations tested on latest staging snapshot

[rithviknishad]

@sainak external_id was hidden too?

[sainak]

Yeah we are using the id field for it right

[rithviknishad]

oh my bad; got confused

[nihal467]

I tested in tunnel provided by @rithviknishad's and added multiple medicines to a patients but partial search is not giving expected results

[rithviknishad]

Alternate approach used. Completed via #1443