pnpm lockfile testing across versions

See notes in lockfile-test.bzl for test cases of each package.

pnpm lockfile edge cases (./cases/*)

Unique test cases hard to cover with normal pnpm workspaces + package.json. Each test case is a pnpm-lock.yaml with a unique filename, see cases/BUILD for how the test cases run on each of those lockfiles.

• isaacs-cliui-v*: a transitive npm: dependency as an alias to use multiple versions of a single package, this is different then a direct npm: dependency
• override-with-alias-url-v9 - a package overridden with a different package
• tarball-no-url-v54 - a package with a tarball but not a full URL