Update dotnet sdk create file example

[stnguyen90]

What does this PR do?

The latest version of our SDKs use InputFile.

Test Plan

Manually generated and got:

using Appwrite;
using Appwrite.Models;

var client = new Client()
    .SetEndPoint("https://cloud.appwrite.io/v1") // Your API Endpoint
    .SetProject("5df5acd0d48c2") // Your project ID
    .SetKey("919c2d18fb5d4...a2ae413da83346ad2"); // Your secret API key

var storage = new Storage(client);

File result = await storage.CreateFile(
    bucketId: "[BUCKET_ID]",
    fileId: "[FILE_ID]",
    file: InputFile.FromPath("./path-to-files/image.jpg"));

Related PRs and Issues

None

Have you read the Contributing Guidelines on issues?

Yes