Added configuration for WebP image style overrides

[Neslee]

• Implement WebP image style overrides #3

Solution

Implemented webP image style override configuration into dxpr_base recipe, from dxpr/dxpr_marketing_cms#57

Checklist

• I have read the CONTRIBUTING.md document.
• My commit messages follow the contributing standards and style of this project.
• My code follows the coding standards and style of this project.
• My code contains no changes that are outside the scope of the issue.
• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to change).
• Need to run update.php after code changes.
• Requires a change to end-user documentation.
• Requires a change to developer documentation.
• Requires a change to QA tests.
• Requires a new QA test.
• I have updated the documentation accordingly.
• All new and existing tests passed.

[jjroelofs]

great,thx!