Support custom request headers

[Dacello]

Currently, it seems like request headers for REST API calls have headers hardcoded, e.g. here when calling put_blob

I would like to add additional headers, such as x-ms-blob-content-md5 which allows sending an MD5 hash for added verification.

Resolved: Additionally, get_blob returns simply {:ok, blob} but we need the response headers as well. In my case its because there is a Content-MD5 header that can be used to enforce upload uniqueness.
Just use Blob.head_blob

https://learn.microsoft.com/en-us/rest/api/storageservices/put-blob?tabs=microsoft-entra-id#request-headers-all-blob-types
https://learn.microsoft.com/en-us/rest/api/storageservices/get-blob?tabs=microsoft-entra-id#request-headers

[Dacello]

UPDATE: I just discovered Azurex.Blob.head_blob which will get me what I need when it comes to the Content-MD5 header. That said, it would still be nice to be able to pass custom headers when we send requests.

[Dacello]

I have come to another realization: if we made the Azurex.Blob.blob_request function public, that would also allow for any necessary custom request headers