OvmfPkg/PlatformBootManagerLib: Init console vars in *BeforeConsole()

OvmfPkg/PlatformBootManagerLib: Init console vars in *BeforeConsole()

The major difference between IntelFrameworkModulePkg/BDS and
MdeModulePkg/BDS is the latter connects the consoles in core
code while the former connects in platform code.
The change initializes the console variables in
PlatformBootManagerBeforeConsole() and removes the console
connection code.
It also removes unused functions: PlatformBdsNoConsoleAction()
and LockKeyboards().

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>