app: Fix for MacOS PATH when run under Finder

[illume]

On at least MacOS, GUI apps do not take on the shell PATH.
However they are needed for kubectl auth plugins, and perhaps other binaries like minikube

Fixes #1885

How to test

• How to test:
  • change main.ts pathInfoDebug = true
  • make app-macos
  • Run the macos app from the Finder (do not launch it from the terminal)
  • See alert message with "previousPath" and "newPath" should match the same path as the terminal/shell.

[illume]

The frontend failure is unrelated to this PR, and is fixed in #1910

[illume]

@ashu8912 to recap where we are up to, and suggestions on next steps...

• the azure/kubelogin isn't working in headlamp (in Headlamp started by terminal, or in Headlamp started by finder). So this is not a good thing to test that this PR is working.
  - [ ] aws-iam-authenticator hasn't been tested yet (@ashu8912 can you do this one?)
• I will outline some steps to test more clearly with the minikube/az binaries as well (which might be on a terminal path but not in the PATH for the user running the app from finder) @illume to do
• there should also be a check to see if the app is NOT being run by the terminal, and in that case there is no need to modify the PATH. @illume to do
• Add a logging of the PATH variable, which would allow us to check that it is equivalent to the terminal one easily

[illume]

Hi @ashu8912 I made changes to the PR.

Also outlined some much simpler testing steps, to just check the PATH from the terminal is being added.

[illume]

@joaquimrocha I've updated the test instructions and added a screen shot showing it works to the PR description.