fix: introduce a class implementation of InstalledPackage interface

[valotas]

No description provided.

[zkochan]

too many changes. Only the pkg parameter should be changed to set only the needed set of fields.

pnpm is written using functional programming. There are no classes in it except the Error objects.

[zkochan]

Actually, I checked the code. Even fewer properties are needed. I'll do this today.

[valotas]

I would like to fix the issues, but your are really fast!

[zkochan]

I appreciate it! Have you tried your fix? Did it fix the issue with memory? Or you want to try the fix once pnpm gets published with it?

[valotas]

I can only try it on Monday as it is not a personal project.