bitbake: event/hob: Add a button for network tests in the proxy settings

This patch allows the user to check the network connectivity in
the "Proxy" page ("Settings" dialog) by adding a button which provides
this functionality. It also disables retrigerring sanity checks if the
proxy values are changed, since now the proxy checks are explicit.
Note that this patch depends on a patch in oe-core
("sanity.bbclass: trigger network tests explicitly"). It will
not work properly if the patch in oe-core is not merged.

[YOCTO #3026]

(Bitbake rev: cb1354d29c0be27aee57b9783c724457ef6725fb)

Signed-off-by: Bogdan Marinescu <bogdan.a.marinescu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/event.py

@@ -566,3 +566,19 @@ class SanityCheckFailed(Event):
         Event.__init__(self)
         self._msg = msg
         self._network_error = network_error
+
+class NetworkTest(Event):
+    """
+    Event to start network test
+    """
+
+class NetworkTestPassed(Event):
+    """
+    Event to indicate network test has passed
+    """
+
+class NetworkTestFailed(Event):
+    """
+    Event to indicate network test has failed
+    """
+