Extend github context with host-workspace

[nikola-jokic]

We encountered an issue where step host was not used when evaluating user inputs.
The PR #1762 fixed this problem, but it introduced another problem for hash files.

hashFiles operates on the host, regardless of whether you are running inside the container or not.

Since inputs are translated based on the step host, we lose the ability to know how to translate back from the container path to the host path.

This change aims to add another context variable to the runner context named host-workspace that will be set to the runner host workspace regardless of whether the action is executed inside the container or not.
Example of the composite action:

name: "test"
runs:
  using: "composite"
  steps:
  - run: |
      echo "${{github.action_path}}"
      echo "${{github.workspace}}" 
      echo "${{github.event_path}}"
    shell: bash
    name: "Just echo"
  - run: echo ${{ hashFiles('**/*.lock')}}
    shell: bash
    name: "test"

Repro of this issue with StepHost evaluation and hash files:

After applying this change:

Related to #716

[abhijeetdhoke]

@nikola-jokic could you please help us to fix this issue we are stuck from last week on same stage, I dont have resolution for this.

[fhammerl]

LGTM