Build the pgrag extensions (rag, rag_bge_small_en_v15, and
rag_jina_reranker_v1_tiny_en) as part of the compute node Dockerfile.
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Co-authored-by: Alexander Bayandin <alexander@neon.tech>
## Problem
Our dockerfiles, for some historical reason, have unconventional names
`Dockerfile.<something>`, and some tools (like GitHub UI) fail to highlight
the syntax in them.
> Some projects may need distinct Dockerfiles for specific purposes. A
common convention is to name these `<something>.Dockerfile`
From: https://docs.docker.com/build/concepts/dockerfile/#filename
## Summary of changes
- Rename `Dockerfile.build-tools` -> `build-tools.Dockerfile`
- Rename `compute/Dockerfile.compute-node` ->
`compute/compute-node.Dockerfile`
