NetworkPkg: Allow user to create a HTTP corporate boot option in setup page.

NetworkPkg: Allow user to create a HTTP corporate boot option in setup page.

This patch updates the HTTP Boot Configuration page to allow the user to create
a corporate mode HTTP boot option, by leaving the URI string empty.
The patch also fix a bug that the L"https://" should use StrnCmp() with Length 8.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Samer El-Haj-Mahmoud <elhaj@hpe.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>