chore(ci): split build jobs

[ghost]

Running these jobs in parallel speeds up overall pipeline time by 10+ minutes.
Tests for specific platforms will also start earlier for faster feedback.

Pitch: https://www.notion.so/snyk/CLI-Speed-Up-Time-to-Build-in-CI-0d7ce418ecd14fa0bd8fac1ac391eea1

Things to note:

• Previously we ran v2's "whiteboxtests" as part of the "Build Artifacts" job for linux/amd64 builds.
  • This is now its own job as running these tests doesn't require building and allows build jobs to be generic.
• We can't use matrix jobs for building v2 like we can for v1 as each v2 job requires a specific v1 job.
  • If we try to make this work within a matrix, it's a lot more complicated than listing the jobs out individually.

How to review:

• Other than ensuring each job still passed, the "Prepare Release" job should list all the same CLIv1 artifacts as before this change.
  • https://app.circleci.com/pipelines/github/snyk/cli/12440/workflows/310229cb-b49b-44b6-a88c-d85848f70ca2/jobs/99017/artifacts
  • You can download and run these artifacts. snyk --version should show the same version as the version artifact.