fix(pnpm): support npm: aliases to packages in alternate registries

[jbedard]

Fixes include:

• pnpm v5-6 aliases to a package with the registry.npmjs.com/ prefix (broke in the last PR)
• pnpm v9 aliases in transitive deps, pointing to packages not in any workspace package.json
• making aliases clearer by changing the internal format to npm: (like specifiers) instead of / prefixes (/alias/version was v5, /alias@version was v6, alias@version is v9 and no longer has the distinguishing prefix so I switched to npm: in our internal structs).

Added tests for each of those cases across lockfile versions.

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Changes are visible to end-users: no

Test plan

• New test cases added

[aspect-workflows]

Test

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193 tests (100.0%) were fully cached saving 53s.

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Test

e2e/bzlmod

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4 tests (100.0%) were fully cached saving 467ms.

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e2e/gyp_no_install_script

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2 tests (100.0%) were fully cached saving 439ms.

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Test

e2e/js_image_oci

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1 test (100.0%) was fully cached saving 9s.

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Test

e2e/npm_link_package

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2 tests (100.0%) were fully cached saving 1s.

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Test

e2e/npm_link_package-esm

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2 tests (100.0%) were fully cached saving 923ms.

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Test

e2e/npm_translate_lock

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1 test (100.0%) was fully cached saving 73ms.

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Test

e2e/npm_translate_lock_empty

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1 test (100.0%) was fully cached saving 73ms.

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e2e/npm_translate_lock_multi

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2 tests (100.0%) were fully cached saving 271ms.

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Test

e2e/npm_translate_lock_partial_clone

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1 test (100.0%) was fully cached saving 117ms.

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Test

e2e/npm_translate_lock_subdir_patch

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1 test (100.0%) was fully cached saving 248ms.

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Test

e2e/npm_translate_package_lock

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1 test (100.0%) was fully cached saving 73ms.

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Test

e2e/npm_translate_yarn_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 73ms.

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Test

e2e/package_json_module

All tests were cache hits

1 test (100.0%) was fully cached saving 520ms.

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Test

e2e/pnpm_lockfiles

All tests were cache hits

25 tests (100.0%) were fully cached saving 9s.

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Test

e2e/pnpm_workspace

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8 tests (100.0%) were fully cached saving 3s.

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Test

e2e/pnpm_workspace_rerooted

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6 tests (100.0%) were fully cached saving 2s.

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Test

e2e/repo_mapping

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2 tests (100.0%) were fully cached saving 451ms.

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Test

e2e/rules_foo

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2 tests (100.0%) were fully cached saving 605ms.

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Test

e2e/vendored_node

All tests were cache hits

1 test (100.0%) was fully cached saving 187ms.

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