Update workflows to package and release standalone binaries

[trxcllnt]

Opening as a draft so it isn't accidentally merged before #343.

This PR is a follow-up to #343 that updates the GHA workflows to build, test, and release the standalone binaries created by @vercel/pkg.

Modifications to dev-containers.yml:

• Fails fast (can remove this)
• Only run Test job when relevant files are modified
• Cache node_modules dirs between jobs/across CI runs
• Update CLI job to build the standalone binaries on ubuntu-20.04, macos-11, and windows-2019
• Update Test job to run a subset of the tests on the standalone binaries (though can expand this to all tests if preferred!)

See here for an example of a successful run.

Modifications to publish-dev-containers.yml:

• Doesn't publish the npm package if run from a repo other than @devcontainers/cli
• Allow running workflow manually
  • Uses the most recent tag to the current commit if releasing manually
  • Allows maintainers test changes to the publish-dev-containers.yml on branches
  • Uploads artifacts to workflow run if Make GitHub Release and Make GitHub Draft Release aren't selected
• Creates a GitHub release w/ changelog and npm package + standalone binaries (supports draft/pre-releases)

See here for an example of a successful release on tag push, and here for the release it generated.

Notes on cross-compiling

• This PR builds the standalone packages on each target OS
  • My attempts to cross-compile Windows and signed (via ldid) MacOS binaries from Ubuntu were unsuccessful
  • The docs say this should work w/ --no-bytecode, but the binaries failed tests on the target OS
  • I can keep investigating this if it's a blocker
• Currently only publishes x86 binaries due to the above, and
  • The GHA runners are x86
  • Windows/MacOS cross-compiling x86 from arm64 possible, but not arm64 from x86
  • Could solve this with QEMU if we can cross-compile Windows/MacOS binaries from Linux

[trxcllnt]

Merging into https://github.com/trxcllnt/devcontainers-cli/tree/fea/pkg (#343)