Support GetRandomBytes in Key Client

[maorleger]

As per https://github.com/Azure/azure-rest-api-specs/blob/c2dce10efdbaffe9358eadb14791a0bcbcabbcb5/specification/keyvault/data-plane/Microsoft.KeyVault/preview/7.3-preview/keys.json#L1223-L1266

I believe the current proposed API is

const bytes: UInt8Array = await keyClient.getRandomBytes(count /* number of bytes */)

Questions:

• Does this return a buffer / byte array or a base64 encoded string?

[chradek]

Does this return a buffer / byte array or a base64 encoded string?

For what it's worth, I like that it currently returns a Uint8Array, since that is an array of bytes and roughly matches browser's getRandomValues() which returns a TypedArray and node.js' randomBytes which returns a Buffer (which extends Uint8Array).

I'd expect that operations that needed to use the output of getRandomBytes would use the byte array, not the base64 string but open to hearing how it's meant to be used if that's not the case.

[maorleger]

Closed via #15955