feat: Add descriptive constants for Azure content filter configuration - Option 1

[KavithaSiva]

Context

Closes SAP/ai-sdk-js-backlog#181.

What this PR does and why it is needed

This PR adds self descriptive constansts for improving Azure content filter configuration.

Autocompletion works with the string key values of AzureFilterThreshold and the numeric allowed values 0,2,4 and 6 coming up in hints.

[KavithaSiva]

This is also another option:

export type AzureContentSafetyThresholdKeys =
  | 'ALLOW_SAFE'
  | 'ALLOW_SAFE_LOW'
  | 'ALLOW_SAFE_LOW_MEDIUM'
  | 'ALLOW_ALL';

export const AzureFilterThreshold: Record<
  AzureContentSafetyThresholdKeys,
  AzureThreshold
> = {
  ALLOW_SAFE: 0,
  ALLOW_SAFE_LOW: 2,
  ALLOW_SAFE_LOW_MEDIUM: 4,
  ALLOW_ALL: 6
};

But then autocomplete looks like this (It doesn't give the value hints, even if I add comments):

And I didn't find a convenient way to use enum and map it to the values of AzureThreshold

[ZhongpinWang]

[q] Any reason why we are not using enum here and modify the type for, e.g., Hate to that enum? Otherwise user would need to know this constant exist without autocompletion's help.

[MatKuhr]

Would modifying the type be a breaking change?

[KavithaSiva]

I discussed with @ZhongpinWang, modifying the type doesn't seem to be a breaking change as in the end they would both resolve to be the same code in JS.

[KavithaSiva]

Closing this PR, in favour of #476, introducing an enum with a new type instead.

[KavithaSiva]

Closed in favour of #485