[Proposal] External Architecture Registration

[jlarson4]

Proposal

Create a public-facing architecture adapter registration API, that allows users to create their own adapters and attach them to TransformerLens's system

Motivation

This allows users to experiment with the Architecture Adapter system without having to fork and modify TransformerLens source directly.

Pitch

• Create a register_adapter method in ArchitectureAdapterFactory that allows custom architectures to be added to the registry\
• Add entry point discovery via pyproject.toml that allows custom packages to register architectures
• Add an additional page to documentation under Contributing with examples for how to use the Architecture Adapter registration system

Checklist

• I have checked that there is no similar issue in the repo (required)

[huseyincavusbi]

Ready to work on these! @jlarson4