Fix an error that could occur when Asset volume for the file field has a subpath

[nikolenko-dmitriy]

Description

• There is the form with a file field
• There is filesystem Local that has base part as @webroot/uploads
• There is an asset volume Forms that uses Local filesystem but also has a subpath forms. So, the final base part for the asset volume Forms is @webroot/uploads/forms
• Asset volume Forms is selected in Wheel Form settings as the volume folder to save uploaded form files.

Steps to reproduce

1. Create the simple form with a file field
2. Fill form fields on the page and also upload some file in a file field
3. On submit the new form entry will be created and the uploaded file will be stored in @webroot/uploads/forms
4. On the next step when Wheel Form plugin tries to send the mail, the error is triggered because it tries to find the uploaded file in @webroot/uploads folder, instead of @webroot/uploads/forms. Please see screenshots below

Craft CMS version

5.5.3

Wheel Form version

4.0.2