escape base64 encoded json token uri strings

[lara-jeftic]

Description

If a token uri is a base64 encoded json, there is a chance the json string is incorrectly escaped and therefore unparseable. this PR attempts to parse the json and if it fails, it escapes the json correctly and then parses it.

Motivation and Context

see ticket here: (https://linear.app/ourzora/issue/CHAIN-790/move-token-uri-escaping-functionality-to-offchain-lib)

How has this been tested?

Screenshots (if appropriate):

Types of changes

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• [X] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.