NetworkPkg/DxeHttpLib: Migrate HTTP header manipulation APIs

NetworkPkg/DxeHttpLib: Migrate HTTP header manipulation APIs

Move HTTP header manipulation functions to DxeHttpLib from
HttpBootSupport.c. These general functions are used by both
Http BOOT and RedfishLib (patches will be sent later).

Signed-off-by: Abner Chang <abner.chang@hpe.com>
Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Cc: Fan Wang <fan.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Nickle Wang <nickle.wang@hpe.com>
Cc: Peter O'Hanley <peter.ohanley@hpe.com>
Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>