Allow user to override initial storage slots in forc-deploy

[sdankel]

Description

Closes #2010

Notes:

• I couldn't use from_reader to deserialize the file contents due to this issue: Fixed json deserialization of array fuel types from the file fuel-vm#643

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).
• 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.

[JoshuaBatty]

thanks