API key header default way

[Bercof]

Is your feature request related to a problem? Please describe.
The default way to set httpClient header is openai-style Authorization: Bearer ... now. But comparing to official python-openai library the default way is Azure-style api_key ... (here is source)
There is only one option to influence api key header: ProviderType.

Describe the solution you'd like
To avoid breaking changes my idea is to introduce new option AuthorizationHeaderType with explicit default value Undefined. At OpenAIService constructor AuthorizationHeaderType may be checked and may be set depending on ProviderType value.

Create enum:

public enum AuthorizationHeaderType
{
    Undefined = 0,
    AuthorizationHeader = 1,
    ApiKey = 2
}

Add new attribute to class OpenAiOptions:

public AuthorizationHeaderType AuthorizationHeaderType { get; set; } = AuthorizationHeaderType.Undefined;

Replace lines switch (settings.ProviderType) {...} at OpenAIService constructor:

if (settings.AuthorizationHeaderType == AuthorizationHeaderType.Undefined)
{
  switch (settings.ProviderType)
  case ProviderType.Azure:
      settings.AuthorizationHeaderType =  AuthorizationHeaderType.ApiKey;
      break;
  case ProviderType.OpenAi:
  default:
      settings.AuthorizationHeaderType =  AuthorizationHeaderType.AuthorizationHeader;
      break;

}

switch (settings.AuthorizationHeaderType)
{
  case AuthorizationHeaderType.ApiKey:
      _httpClient.DefaultRequestHeaders.Add("api-key", settings.ApiKey);
      break;
  case AuthorizationHeaderType.AuthorizationHeader:
  default:
      _httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {settings.ApiKey}");
      break;
}

Describe alternatives you've considered
AuthorizationHeaderType attribute at OpenAiOptions may be nullable.

[kayhantolga]

https://platform.openai.com/docs/api-reference/authentication I think I am confused with this issue. I am not sure if they updated the code, but in OpenAI documentation, they suggest using a Bearer token, which the library is already doing. Currently, the library already sets the x-api-key for Azure connection and Bearer token for OpenAI connection. The Python library also does the same thing, and your suggestion is also the same. Am I missing something? I am not sure. Could you help me to understand what is wrong?