feat: create cloud saving/loading of route layers

[jamescalam]

We will add a "Route Hub" which for the foreseeable future will using Hugging Face Hub as a "RouteLayer repository" allowing users to save, load, and share route layers.

Should include:

• Saving/loading of all Routes in a route layer, including their thresholds, any function calling schema, and description
• Saving/loading of encoder information
• Anything else needed to make saving/loading fully automated and easy
• Tagging system on HF so we and users can filter for and search specifically for route layer datasets on HF

Users will need an HF account and API keys for this to work.

Can refer to this example for a minimal version of this functionality

[codecov]

Codecov Report

Attention: Patch coverage is 17.10526% with 63 lines in your changes are missing coverage. Please review.

Project coverage is 78.48%. Comparing base (29762f0) to head (4fc90d3).

Files	Patch %	Lines
semantic_router/layer.py	17.10%	63 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #164      +/-   ##
==========================================
- Coverage   80.39%   78.48%   -1.91%     
==========================================
  Files          44       44              
  Lines        2443     2519      +76     
==========================================
+ Hits         1964     1977      +13     
- Misses        479      542      +63     

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