Rename post table to program

[akarki2005]

Proposed Changes

This PR renames the Post and PostCategory tables in the Courseography database to Program and ProgramCategory respectively. It also introduces a new CLI option database-migrate which applies these migrations; this addition has been reflected in the README.md file.

Type of Change

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Type	Applies?
🚨 Breaking change (fix or feature that would cause existing functionality to change)
✨ New feature (non-breaking change that adds functionality)
🐛 Bug fix (non-breaking change that fixes an issue)
🎨 User interface change (change to user interface; provide screenshots)
♻️ Refactoring (internal change to codebase, without changing functionality)	X
🚦 Test update (change that only adds or modifies tests)
📦 Dependency update (change that updates a dependency)
🔧 Internal (change that only affects developers or continuous integration)

Checklist

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Questions and Comments

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