Feature: #88238 - FeatureToggle: form.legacyUploadMimeTypes

See Issue #88238

Description

The feature toggle form.legacyUploadMimeTypes makes it possible to enable some predefined allowedMimeTypes in FileUpload and ImageUpload form elements.

These MIME types are enabled through this feature toggle by default as of TYPO3v10 and will be removed completely in TYPO3v11.

Impact

Full control over file upload MIME type validation can be achieved by disabling this flag and explicitly listing all allowed MIME types.