fix: show path in external_directory permission prompt

[jamesbornholt]

Without this, external_directory permissions prompts, at least for read tools, didn't show a path at all. You could figure it out by seeing which tool usages were pending, but that was annoying especially if it was a different session triggering the prompt. The "always allow" confirmation screen did include the path though.

• Update bash tool to ask for each external directory individually (consistent with read/edit/patch tools)
• Populate metadata.parentDir in bash tool's external_directory request
• Display absolute path for external directories instead of relative

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found one PR that is closely related to PR #7272:

Related PR:

• PR Improve permission request messages; add external directory check for write tool #6714: "Improve permission request messages; add external directory check for write tool"
  • Improve permission request messages; add external directory check for write tool #6714
  • This PR also addresses permission request messages for external directories and appears to involve similar improvements to how permission prompts display information to users.

This PR is related as both address improving the clarity and information displayed in external_directory permission prompts, though they may be targeting different tools (write tool vs bash tool).