chore: deprecate ipfs-on-path

[lidel]

"ipfs-on-path" opt-in feature aims to add ipfs binary to PATH on every platform.
Unfortunately that is brittle, buggy, way better if user does this by hand for now.

We have a bunch of creative hacks that make it work most of the time, but after looking how we do it, I don't feel comfortable keeping this as a feature:

• relies on brittle scripts which break over time and degrade user experience
• we don't have bandwidth for maintaining this feature for all platforms
• windows requires powershell, which a lot of users dont have on PATH (sic!)
• linux requires polkit, not every distro uses that
  • even so, iiuc it is not even possible to make it work in sandboxed contexts like Snap or AppImage
• adding to global PATH is a security-sensitive task and I don't think a desktop app should do this

👉 This PR keeps the feature enabled for existing users, but will hide menu item for new users, so it is phased out over time. If you want ipfs on your PATH follow https://docs.ipfs.io/install/command-line/

Just to illustrate, issues caused by ipfs-on-path:
#1357
#1301
#1761
#1694
#1755