citra_qt: Removed autogenerated files from repo and fixed build issues.

Qt automatically generates header files from the *.ui files on build. These auto-generated files were previously checked into our repository, which should not have been the case. This pull request removes said headers from the repository. Furthermore, the Linux build expected these to be checked in (presumably after having been tested/checked in by a Windows user). This fixes the build environment on Linux.

There is still a minor issue that should probably eventually be resolved: All *.ui files (even those in subdirectories, e.g. "./src/citra_qt/debugger/ui_callstack.ui") generate their headers in the root project directory ("./src/citra_qt/") on Windows, and in the build root project directory ("./build/citra_qt") on Linux. The build root project directory was already added to the include directories in the CMakeLists file, so the simplest fix to make this work on Windows was to just add the ./src/citra_qt/ folder as an include directory in the VS properties file.