Dev container

[lejouson]

Description

Turn Docker image into a Dev Container.

Related Issue(s)

Closes #19

Changes Made

Move Dockerfile into .devcontainer folder. Add devcontainer.json file. Modify build workflow to pre-build dev container image first if needed. Pin base layer version.

Testing

Ensure build ends successfully.

Checklist

Please check the following items before submitting this PR:

• The code builds and runs without errors.
• All existing tests pass, and new tests have been added where appropriate.
• The code follows the project's coding standards and style guide.
• Documentation has been updated where necessary.

Additional Notes

Check dev containers documentation.