Change svn:mime-type property on all Unicode files (extension .uni) in edk2

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: lhauch <larry.hauch@intel.com>
Reviewed-by: Samer El-Haj-Mahmoud <samer.el-haj-mahmoud@hp.com>


git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/OvmfPkg@15806 6f19259b-4bc3-4df7-8a09-765794883524