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/styles/index.scss b/app/server-control/styles/index.scss
index 7171a7e..cd91860 100644
--- a/app/server-control/styles/index.scss
+++ b/app/server-control/styles/index.scss
@@ -3,3 +3,4 @@
 @import "./remote-console.scss";
 @import "./server-led.scss";
 @import "./kvm.scss";
+@import "./virtual-media.scss";