feat: allow building typed data from signable order

[Zer0dot]

This PR allows building typed data from a signable order, which can then be sent to another service to sign using e.g. an EOA.

It also adds functionality to post externally signed orders.

[codecov]

Codecov Report

❌ Patch coverage is 97.26027% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.10%. Comparing base (37859d1) to head (3dd3495).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/clob/client.rs	97.26%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #106      +/-   ##
==========================================
+ Coverage   86.84%   87.10%   +0.26%     
==========================================
  Files          30       30              
  Lines        4377     4450      +73     
==========================================
+ Hits         3801     3876      +75     
+ Misses        576      574       -2     

Flag	Coverage Δ
rust	87.10% <97.26%> (+0.26%)	⬆️

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