[Bug]: small regression in mailmeta

### Apache Hop version?

2.18-SNAPSHOT

### Java version?

21

### Operating system

macOS

### What happened?

3 fields have been renamed without adding the key to HopMetadataProperty:

dynamicFieldname -> dynamicFieldName
sourcefilefoldername -> sourceFileFolderName
sourcewildcard -> sourceWildCard

### Issue Priority

Priority: 2

### Issue Component

Component: Transforms