pnpm install --if-needed

[vergilfromadyen]

Proposal:
Doing pnpm install several times in a row is relatively fast but it would be great to have an option to skip it if the workspace is up to date.
This is especially impactful on large monorepos with many workspaces.

Use-case:
When doing a git pull from the main branch, if the pulled commits carry dependency updates, the project may behave unexpectedly and developers might end up developing against code that is no longer there. A hook or a package.json script can solve that without noticeably slowing down the system.

Mechanism:
For pnpm I believe this can be checked by comparing pnpm-lock.yaml to node_modules/.pnpm/lock.yaml. If pnpm-lock.yaml is newer, then the workspace is not up to date, and pnpm install should run.