Add glossary infrastructure and hover/click definitions.

[Ayushmaan06]

Description
Fixes #33117
This pull request introduces a new glossary infrastructure to the OpenPilot documentation. The changes include:

• Glossary Terms: Added terms to docs/glossary.json .
• Glossary Page: Created a glossary page under docs/concepts/glossary.md.
• Hover/Click Definitions: Implemented functionality to show definitions of glossary terms when hovered over or clicked using /static/js/glossary.js and static/main.css.

These updates enhance the documentation by providing easy access to definitions directly within the documentation pages, improving user understanding of OpenPilot concepts.

Verification

• Confirmed that the new glossary terms are correctly linked and accessible from documentation pages.

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