ArmVirtPkg/PlatformBootManagerLib: follow PlatformBootManagerLib interfaces

ArmVirtPkg/PlatformBootManagerLib: follow PlatformBootManagerLib interfaces

"IntelFrameworkModulePkg/Include/Library/PlatformBdsLib.h" declares the
following interfaces:

- PlatformBdsInit
- PlatformBdsPolicyBehavior
- PlatformBdsBootFail
- PlatformBdsBootSuccess
- PlatformBdsLockNonUpdatableFlash
- LockKeyboards

From these, we've been using PlatformBdsInit() and
PlatformBdsPolicyBehavior().

"MdeModulePkg/Include/Library/PlatformBootManagerLib.h" declares the three
interfaces below:

- PlatformBootManagerBeforeConsole
- PlatformBootManagerAfterConsole
- PlatformBootManagerWaitCallback

Comparing the BdsEntry() functions between
- "IntelFrameworkModulePkg/Universal/BdsDxe/BdsEntry.c" and
- "MdeModulePkg/Universal/BdsDxe/BdsEntry.c",
we can establish the following mapping:

IntelFrameworkModulePkg              MdeModulePkg
  BdsEntry()                           BdsEntry()
    PlatformBdsInit()   <--------------> PlatformBootManagerBeforeConsole()
    dispatch Driver#### <--------------> dispatch Driver####
                                         connect consoles
    PlatformBdsPolicyBehavior() <------> PlatformBootManagerAfterConsole()

The difference in connecting the consoles will be addressed in a later
patch, now we just rename the functions according to the mapping above,
and copy the call site comments from MdeModulePkg's BdsEntry().

For the third interface, PlatformBootManagerWaitCallback(), add an empty
implementation (and copy the comment from the library class header).
Platform BDS can use this callback to draw a progress bar, for example.

This patch parallels OvmfPkg commit a7566234e92c.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ruiyu Ni <ruiyu.ni@Intel.com>