Change UpdateService POST URI

As d01e32c3786f2fbbb70c9724a87cf979b4a06232 found, the Redfish
specification doesn't allow a direct POST handler on UpdateService.
Ideally clients would be following the specification, and relying on
the HttpPushUri as the spec requires, so we could simply make this
change.  Unfortunately, a quick polling of the community shows that a
significant number of instances, including the Redfish cheat sheet, and
the robot tests, have hardcoded the non-spec behavior.  This commit is
present to give a trap door to allow easier porting of this behavior to
the specification.

The old uri is left, and now returns a WARNING http field, indicating
that the uri is deprecated, in case clients have ignored the Redfish
specification.

Tested:
Ran firmware update instructions from
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/53664

Test gave the same result as previously.

/redfish/v1/UpdateService returns an HttpPushUri that matches the above.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I7427f461d151c9460160b0b9b366dca5aefc49d5
diff --git a/meson_options.txt b/meson_options.txt
index d943222..f2b4f37 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -214,6 +214,17 @@
 )
 
 option(
+    'redfish-post-to-old-updateservice',
+    type: 'feature',
+    value: 'enabled',
+    description: '''Allows POST to /redfish/v1/UpdateService, counter to
+                    the redfish specification.  Option provided to allow
+                    potential users to move away from using this endpoint.
+                    Option will be removed Q4 2022.'''
+)
+
+
+option(
     'https_port',
     type: 'integer',
     min: 1,