MdeModulePkg/Variable: Parameterize GetNextVariableInternal () stores

MdeModulePkg/Variable: Parameterize GetNextVariableInternal () stores

The majority of logic related to GetNextVariableName () is currently
implemented in VariableServiceGetNextVariableInternal (). The list
of variable stores to search for the given variable name and variable
GUID is defined in the function body. This change adds a new parameter
so that the caller must pass in the list of variable stores to be used
in the variable search.

Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>