feat(client): support streaming multipart file uploads

[junliurs]

Motivation

Solution

[codecov]

Codecov Report

❌ Patch coverage is 89.80892% with 32 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.90%. Comparing base (ce5c0b6) to head (73ccf24).

Files with missing lines	Patch %	Lines
volo-http/src/client/multipart.rs	88.47%	31 Missing ⚠️
volo-http/src/client/request_builder.rs	97.77%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #658      +/-   ##
==========================================
+ Coverage   46.20%   46.90%   +0.70%     
==========================================
  Files         163      164       +1     
  Lines       20307    20621     +314     
==========================================
+ Hits         9382     9672     +290     
- Misses      10925    10949      +24     

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