Move Virtual Media files and route

"Virtual media" was already part of the "Server control" submenu but
the files were at app/configuration and the route was /configuration.

Marta Mazur did a similar file and route move here as part of
supporting multiple Virtual Media endpoints:
https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-webui/+/25218

Tested: Built and loaded on a Witherspoon. The VM route is now:
        #/server-control/virtual-media. Was able to use the VM
        panel.
Change-Id: Iec46a8ece7ddfbc356bc1e71875def70c4418027
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/app/server-control/index.js b/app/server-control/index.js
index 1b8aad5..8bf03b4 100644
--- a/app/server-control/index.js
+++ b/app/server-control/index.js
@@ -53,6 +53,12 @@
                 'controller': 'kvmController',
                 authenticated: true
               })
+              .when('/server-control/virtual-media', {
+                'template':
+                    require('./controllers/virtual-media-controller.html'),
+                'controller': 'virtualMediaController',
+                authenticated: true
+              })
               .when('/server-control', {
                 'template':
                     require('./controllers/power-operations-controller.html'),