Adding functionality for dirhash in cli

[matglas]

What this PR does / why we need it

Adding the dirhash-glob arguments

Which issue(s) this PR fixes (optional)

Depends on: in-toto/go-witness#223

Fixes: #216 and in-toto/go-witness#65

Acceptance Criteria Met

• Docs changes if needed
• Testing changes if needed
• All workflow checks passing (automatically enforced)
• All review conversations resolved (automatically enforced)
• DCO Sign-off

Special notes for your reviewer:

Todo's

• PR merged for checks to pass: Adding functionality for dirhash in library go-witness#223
• discuss what documentation is needed.
  • idea to add subject types to the attestor documentation for easier understanding of the different subjects.
  • examples or reasoning for using dirhash. also mentioning the downsides for certain use cases.

[netlify]

✅ Deploy Preview for witness-project canceled.

Name	Link
🔨 Latest commit	95d1c7e
🔍 Latest deploy log	https://app.netlify.com/sites/witness-project/deploys/664cefa1ac4d630007d3d110

[matglas]

@jkjell @ChaosInTheCRD I updated both PRs with the latest updates and added changes that we discussed during the Community call. Let me know if you see anything that still needs to be addressed.