Asset custom fields are ignored

[Draykee]

Describe the bug
AssetService.create(ctx: RequestContext, input: CreateAssetInput) ignores input.customFields

vendure/packages/core/src/service/services/asset.service.ts

Line 238 in e4a795f

const result = await this.createAssetInternal(ctx, stream, filename, mimetype);

export type CreateAssetInput = {
  file: Scalars['Upload'];
  tags?: Maybe<Array<Scalars['String']>>;
  customFields?: Maybe<Scalars['JSON']>;  //< is ignored
};

To Reproduce
Steps to reproduce the behavior:

1. Execute a createAssets mutation with customFields input
2. Custom fields are ignored

Expected behavior
Custom fields are properly parsed and present in the database asset table