feat(patch): support npm: registry aliases in npm patch

[manzoorwanijk]

npm patch add <alias> for an npm: registry alias looked the alias name up as a real package, so it fetched the wrong tarball or failed. This PR makes add, commit and update fetch the alias target's tarball while keying the selector and patch file on the alias name, which is what the install engine matches.

• add accepts the alias name (my-lodash) or the full spec (my-lodash@npm:lodash@4.17.21) and resolves the real package from the installed nodes or the declared npm: spec (patch.js).
• The edit dir gets a .npm-patch-alias.json marker so commit writes my-lodash@<version>. The marker is left out of the diff and checked against the edited package.
• update rebases the real package's tarballs and keeps the marker through a conflicted rebase.
• A name installed as two different packages at one version fails with EPATCHAMBIGUOUS, and an explicit alias that disagrees with the installed package fails with EPATCHALIAS.
• npm patch add lodash suggests the alias name when lodash is installed only through an alias.
• Documented alias usage in npm-patch.md.

References

Follow-up to #9439

[manzoorwanijk]

CC: @reggi @martinrrm