Implement a more reliable TOC version check (using Blizzard's CDN)

[rdw-software]

A bit more involved, but allows for scripting more complex interactions (like automatically syncing versions) later on.

Improvements that could be considered in the future, but aren't yet included:

• Fetching from the CDN programmatically instead of via curl (CLI)
• Integrating the version check with the actual test suite
• Supporting multiple TOC files per module, e.g., for Retail/Classic/PTR
• More and/or better sanity checks for the actual TOC values
• Configurable CDN API endpoints (not sure if that's really useful?)