Add missing PromptBuilder convenience wrappers to control media output

[felixarntz]

The PromptBuilder was missing methods to control 3 ModelConfig properties:

• outputMediaOrientation
• outputMediaAspectRatio
• outputSpeechVoice

Additionally, this PR fixes an odd but somewhat important bug with the usingStopSequences method not working at all (it needs to set the top-level key, not a key in customOptions).

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.48%. Comparing base (30a1506) to head (1134643).

Additional details and impacted files

@@             Coverage Diff              @@
##              trunk     #218      +/-   ##
============================================
+ Coverage     87.45%   87.48%   +0.02%     
- Complexity     1194     1197       +3     
============================================
  Files            60       60              
  Lines          3858     3867       +9     
============================================
+ Hits           3374     3383       +9     
  Misses          484      484              

Flag	Coverage Δ
unit	87.48% <100.00%> (+0.02%)	⬆️

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[felixarntz]

@JasonTheAdams One other thing to consider here is that we also don't support setting custom options via PromptBuilder convenience methods - they can only be set by using the slightly more complex usingModelConfig method.

Maybe that's still a reasonable path forward, because using those is more advanced and assumes extra responsibility on the caller - they will need to know whether the API supports a specific custom option or not - but I wanted to bring it up so we can consider whether or not to add a convenience method for them.

If we want to include that in the PromptBuilder, it could be a simple PromptBuilder::usingCustomOption(string $option, $value).