chassis: replace lambda with inline functions

It has been a convention that request route functions take inline
functions instead of lambdas. The benifets include less indents,
beging more readable + unit test-able (take a look at the unit test that
this commit adds for example).

This commit also fixed neccessary headers to make the test compile. The
headers of the unit test source is a complete list. But headers of the
core codes are not complete. These header clean up will be done in a
separate effort once https://gerrit.openbmc.org/c/openbmc/bmcweb/+/55138
is submitted.

Tested:
1. no service validator errors on real hardware.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I4b23ba54707cea947b5db771c72aa64899041511
diff --git a/redfish-core/lib/redfish_util.hpp b/redfish-core/lib/redfish_util.hpp
index e050594..04d6ceb 100644
--- a/redfish-core/lib/redfish_util.hpp
+++ b/redfish-core/lib/redfish_util.hpp
@@ -17,6 +17,10 @@
 #ifndef BMCWEB_ENABLE_REDFISH_ONE_CHASSIS
 
 #include <dbus_utility.hpp>
+#include <sdbusplus/asio/property.hpp>
+
+#include <charconv>
+
 namespace redfish
 {