Hash StorageKey slot for Admin library

[bitzoic]

Type of change

• Improvement (refactoring, restructuring repository, cleaning tech debt, ...)

Changes

The following changes have been made:

• Adds the string "admin" and hashes with the bits of an Identity when creating the storage slot to storage an admin.

Notes

• Reported in the Fuel Attackathon

Checklist

• [x] I have linked to any relevant issues.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [x] I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • [ ] If my change requires substantial documentation changes, I have requested support from the DevRel team
• [x] I have added tests that prove my fix is effective or that my feature works.
• [x] I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• [x] I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• [x] I have requested a review from the relevant team or maintainers.
• [x] I have updated the changelog to reflect the changes on this PR.

[SwayStar123]

Id prefer a longer and more specific string for the digest, to avoid the possibility of collisions more (something like "sway_libs_owner"), but ill leave that to your discretion