We were forgetting to preserve the m_drag and m_mime_data members of
WindowServer::MouseEvent when making a translated copy.
This didn't affect any reachable code paths before this change.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
