[steps] Resolve absolute working_directory paths from repository root

[sjchmiela]

Why

With Workflows I expect more and more users will want to execute scripts related less to mobile app, in directories other than that of the mobile app.

Currently, working_directory works like this:

• relative paths get resolved from the base directory (mobile app directory) — working_directory: scripts if base directory is apps/mobile ends up being /home/expo/build/apps/mobile/scripts
• absolute paths get resolved from VM root — working_directory: /usr/local/bin ends up being /usr/local/bin.

This makes it cumbersome to execute scripts in directories other than that of mobile app. Say, a user wants to execute scripts in /apps/web. If base directory is apps/mobile, they'd need to use ../web. This makes working_directory coupled to base directory set in GitHub repository settings.

How

Here I'm special-casing absolute working_directory paths. I expect very few people to need to execute scripts in FS-absolute paths (/usr/local/bin). So now it is going to work like this:

• (unchanged) relative paths get resolved from the base directory (mobile app directory) — working_directory: scripts if base directory is apps/mobile ends up being /home/expo/build/apps/mobile/scripts
• absolute paths get resolved from repository root — working_directory: /usr/local/bin ends up being /home/expo/build/usr/local/bin.

Test Plan

Adjusted tests.

Also tested manually. A workflow like

jobs:
  test:
    steps:
      - run: pwd
      - run: pwd
        working_directory: /
      - run: pwd
        working_directory: ./
      - uses: eas/checkout
      - run: pwd
        working_directory: scripts
      - run: pwd
        working_directory: /apps/web

produces output like this