initial support for Mode and ModTime on Node interface

[kstuart]

Adds support for storing and retrieving UnixFS v1.5 file mode and last modification time.

Mode and ModTime support on:

• Files
• LinkFiles
• Webfiles
• Directories

Relates to ipfs/kubo/issues/6920

[welcome]

Thank you for submitting this PR!
A maintainer will be here shortly to review it.
We are super grateful, but we are also overloaded! Help us by making sure that:

• The context for this PR is clear, with relevant discussion, decisions
  and stakeholders linked/mentioned.

• Your contribution itself is clear (code comments, self-review for the
  rest) and in its best form. Follow the code contribution
  guidelines
  if they apply.

Getting other community members to do a review would be great help too on complex PRs (you can ask in the chats/forums). If you are unsure about something, just leave us a comment.
Next steps:

• A maintainer will triage and assign priority to this PR, commenting on
  any missing things and potentially assigning a reviewer for high
  priority items.

• The PR gets reviews, discussed and approvals as needed.

• The PR is merged by maintainers when it has been approved and comments addressed.

We currently aim to provide initial feedback/triaging within two business days. Please keep an eye on any labelling actions, as these will indicate priorities and status of your contribution.
We are very grateful for your contribution!

[hacdias]

This repository has been moved to https://github.com/ipfs/go-libipfs. There is not an easy way to transfer PRs, so if you would like to continue with this PR then please re-open it in the new repository and link to this PR.