Add RAFT devcontainers

[trxcllnt]

Description

This PR adds some devcontainers to help simplify building the RAFT C++ and Python libraries.

It also adds an optional job to the pr.yaml to build the RAFT libs in each devcontainer, so the build caches are populated for devs by CI.

A devcontainer can be launched by clicking the "Reopen in Container" button that VSCode shows when opening the repo (or by using the "Rebuild and Reopen in Container" command from the command palette):

Clicking this button will cause VSCode to prompt the user to select one of these devcontainer variants:

On startup, the devcontainer creates or updates the conda/pip environment using raft/dependencies.yaml. The envs/package caches are cached on the host via volume mounts, which are described in more detail in .devcontainer/README.md.

The container includes convenience functions to clean, configure, and build the various RAFT components:

$ clean-raft-cpp # only cleans the C++ build dir
$ clean-pylibraft-python # only cleans the Python build dir
$ clean-raft # cleans both C++ and Python build dirs

$ configure-raft-cpp # only configures raft C++ lib

$ build-raft-cpp # only builds raft C++ lib
$ build-pylibraft-python # only builds raft Python lib
$ build-raft # builds both C++ and Python libs

• The C++ build script is a small wrapper around cmake -S ~/raft/cpp -B ~/raft/cpp/build and cmake --build ~/raft/cpp/build
• The Python build script is a small wrapper around pip install --editable ~/raft/cpp

Unlike build.sh, these convenience scripts don't install the libraries after building them. Instead, they automatically inject the correct arguments to build the C++ libraries from source and use their build dirs as package roots:

$ cmake -S ~/raft/cpp -B ~/raft/cpp/build
$ CMAKE_ARGS="-Draft_ROOT=~/raft/cpp/build" \ # <-- this argument is automatic
  pip install -e ~/raft/cpp

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[trxcllnt]

/ok to test

[trxcllnt]

/ok to test

[trxcllnt]

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[trxcllnt]

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[trxcllnt]

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[trxcllnt]

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[trxcllnt]

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[trxcllnt]

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[trxcllnt]

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[trxcllnt]

/ok to test

[trxcllnt]

/ok to test

[cjnolet]

Does this imply that you've actually gotten RAFT compiling w/ clang?

[trxcllnt]

No, this file is for the clang language server daemon to provide C++ and CUDA intellisense.

[cjnolet]

I'll admit I'm no docker expert but the changes here LGTM in general.

[trxcllnt]

/ok to test

[cjnolet]

/merge