feat: Support custom destination

[ZhongpinWang]

Context

Closes SAP/ai-sdk-js-backlog#163.

Caution

Option 1: Do not merge until #335 is merged and custom destination is also supported in document grounding with documentation added.
✔️ Option 2: Merge this PR first, then adapt #335 to support custom destination in document grounding.

With this PR, you can provide your own destination to execute any request.

For pure clients like ai-api, provide destination when calling execute() method:

await DeploymentApi.deploymentDelete(deploymentId, {
  'AI-Resource-Group': 'default'
}).execute({
  destinationName: 'destinationName'
});

For azure-openai, orchestration and langchain clients, provide destination with the constructor:

new AzureOpenAiChatClient('gpt-4', {
  destinationName: 'destinationName'
});

new OrchestrationClient(
  {
    templating: {
      template: [{ role: 'user', content: 'Hello!' }]
    },
    llm: {
      model_name: 'gpt-35-turbo-16k',
      model_params: {}
    }
  },
  {
    resourceGroup: 'resourceGroup'
  },
  {
    destinationName: 'destinationName'
  }
);

new AzureOpenAiChatClient(
  {
    modelName: 'gpt-4o',
    modelVersion: '24-07-2021',
    resourceGroup: 'my-resource-group'
  },
  {
    destinatioName: 'my-destination'
  }
);

Definition of Done

• Code is tested (Unit, E2E)
• [ ] Error handling created / updated & covered by the tests above
• Documentation updated
• (Optional) Aligned changes with the Java SDK
• (Optional) Release notes updated (Double check again)

[deekshas8]

Please fix the versioning and then it's good to go.

Changes applied

[KavithaSiva]

Mostly looks good, Just clarifying two questions before approving :)

[KavithaSiva]

LGTM