MdeModulePkg/HiiDatabase: Handle questions with Bit VarStore

MdeModulePkg/HiiDatabase: Handle questions with Bit VarStore

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=545

For oneof/numeric/checkbox, their storage may be bit field.
When generating <ConfigAltResp> string to get default value
for these questions, we need to parse the Ifr data to get
the bit Varstore info,and then generating the correct
<ConfigAltResp> string.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>