Add proxy_owner() function to the SRC-14 standard

[bitzoic]

Type of change

• Bug fix
• New feature

Changes

The following changes have been made:

• Adds proxy_owner() function
• Discourages the use of the SRC-5 ownership standard when implementing the SRC-14 standard
• Updates examples with proxy_owner()

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• 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
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.
• I have updated the changelog to reflect the changes on this PR.

[IGI-111]

What's the reasoning behind having a specific function instead of implementing SRC5?

Edit: never mind I read the rest of the change