feat(metagen): typescript client file upload

[luckasRanarison]

• Closes MET-768.

Migration notes

---

• The change comes with new or modified tests
• Hard-to-understand functions have explanatory comments
• End-user documentation is updated to reflect the change

[linear]

MET-768 Add file upload support for TypeScript metagen client

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.66%. Comparing base (0787087) to head (95f450e).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #934      +/-   ##
==========================================
- Coverage   77.68%   77.66%   -0.03%     
==========================================
  Files         149      151       +2     
  Lines       18500    18564      +64     
  Branches     1795     1799       +4     
==========================================
+ Hits        14372    14417      +45     
- Misses       4105     4123      +18     
- Partials       23       24       +1     

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