SecurityPkg: SecureBootConfigDxe: Updated invocation pattern

SecurityPkg: SecureBootConfigDxe: Updated invocation pattern

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3909

This change is in pair with the previous SecureBootVariableLib change,
which updated the interface of `CreateTimeBasedPayload`.

This change added a helper function to query the current time through
Real Time Clock protocol. This function is used when needing to format
an authenticated variable payload.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Signed-off-by: Kun Qin <kun.qin@microsoft.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Michael Kubacki <michael.kubacki@microsoft.com>