clipbrd: Load the clipboard contents from a file

The patch adds basic support for loading the clipboard contents from a file.
It should load most clipboard formats except CF_METAFILEPICT/CF_DSPMETAFILEPICT,
CF_BITMAP/CF_DSPBITMAP and private formats in the range of CF_PRIVATEFIRST -
CF_PRIVATELAST from files compatible with Windows Clipbook Viewer.