chore: use circleci cli to package ci configurations

[cacieprins]

• Closes

Additional details

While the line count of the main workflows.yml has increased quite a bit, this is because circleci config pack unrolls/expands all anchors in the source yml files.

circleci config pack uses the FYAML convention to be able to break yaml files into smaller, easier to digest chunks.

This PR:

• migrates workflows.yml to .circleci/src/workflows
• defines a new pull-request workflow, which at the moment is identical to linux-x64 except it does not include references to any of the jobs excluded by the main build filters
• migrates config.yml to .circleci/src/config
• adds a husky pre-commit hook to pack directories in .circleci/src to a yaml file defined by the directory name in .circleci/
• additionally, runs circleci config validate on these packed yml files, to ensure that they are valid circleci configs

Steps to test

How has the user experience changed?

PR Tasks

• Have tests been added/updated?
• Has a PR for user-facing changes been opened in cypress-documentation?
• Have API changes been updated in the type definitions?