The Upload component has the option to configure it to accept single or multiple files for upload. 

When the component is configured to accept only one file, the text in its Select button should be in singular form - "Select file..." instead of "Select files..."

Describe the bug
With the current Upload implementation, the component doesn't provide an option to filter the files that are selected for upload if the auto-upload property is set to true.

Currently, the files can be filtered only if the auto-upload is set to false as in this StackBlitz example.

To Reproduce

1. Open this StackBlitz example with auto-upload property set to true
2. Select multiple files + one that has the letter "g" in its name

Expected behavior
The file with the letter "g" should not be uploaded

• As a possible solution for the issue, we can provide an event that is triggered before the file upload and when the event is triggered, the files will be filtered.