feat: custom file size limit and mime types at bucket level

[dshukertjr]

What kind of change does this PR introduce?

Feature

Dart implementation of this supabase/storage-js#151

What is the new behavior?

It is now possible to specify, file_size_limit and allowed_mime_types when creating a bucket.
These limits will be imposed during the upload of an asset, allowing you to validate server side the values

Example:

// Create Bucket with file size limit 20mb
await storage.createBucket(
  newBucketName,
  const BucketOptions(
    public: true,
    fileSizeLimit: 20000000, // 20 mb
    allowedMimeTypes: ['image/jpeg'],
  ),
);

// load the file
final bigFile = ... // 1GB

// Upload
await storage.from(bucketName).upload(uploadPath, bigFile); // throws an error