user_mgr: move constructor codes to separate func

Rafactorred the code so that the AccountPolicy part is moved into a
separate function out of the constructor. This is alligned with
existing code: |initUserObject|.

Tested: code moving only.

Before this serial of code, coverage is
  lines......: 61.7% (1217 of 1973 lines)
  functions..: 77.9% (173 of 222 functions)
  branches...: 32.2% (1852 of 5746 branches)

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I83fdc79a12c64039217605ed65def2f2352d7ef6
diff --git a/user_mgr.hpp b/user_mgr.hpp
index a535cc2..53097a8 100644
--- a/user_mgr.hpp
+++ b/user_mgr.hpp
@@ -40,6 +40,7 @@
 
 inline constexpr size_t ipmiMaxUsers = 15;
 inline constexpr size_t maxSystemUsers = 30;
+inline constexpr uint8_t minPasswdLength = 8;
 
 using UserMgrIface = sdbusplus::xyz::openbmc_project::User::server::Manager;
 using UserSSHLists =
@@ -333,6 +334,8 @@
      */
     void throwForInvalidGroups(const std::vector<std::string>& groupName);
 
+    void initializeAccountPolicy();
+
   private:
     /** @brief sdbusplus handler */
     sdbusplus::bus_t& bus;