Rename schema DevicePPID to use PascalCase

**Problem description**
Automated CAMARA validation reports a warning because DevicePPID is not Pascal Case

**Expected behaviour**
Rename schema DevicePPID to use PascalCase and avoid CAMARA validation error

**Alternative solution**
Could just continue to justify using DevicePPID as the name, but probably not worth the effort

**Additional context**
None