This adds support for peer dependencies in npm packages.
1. If not found higher in the tree (ancestor and ancestor siblings),
peer dependencies are resolved like a dependency similar to npm 7.
2. Optional peer dependencies are only resolved if found higher in the
tree.
3. This creates "copy packages" or duplicates of a package when a
package has different resolution due to peer dependency resolution—see
https://pnpm.io/how-peers-are-resolved. Unlike pnpm though, duplicates
of packages will have `_1`, `_2`, etc. added to the end of the package
version in the directory in order to minimize the chance of hitting the
max file path limit on Windows. This is done for both the local
"node_modules" directory and also the global npm cache. The files are
hard linked in this case to reduce hard drive space.
This is a first pass and the code is definitely more inefficient than it
could be.
Closes #15823
This commit changes lockfile to be "additive" - ie. integrity check only fails if
file/package is already specified in the lockfile, but its integrity doesn't match.
If file/package is not present in the lockfile, it will be added to the lockfile and
the lockfile will be written to disk.
This commit changes "npm:" specifier handling to respect "--cached-only" flags and adds "Download" messages for npm registry api calls.
Co-authored-by: David Sherret <dsherret@gmail.com>
