This change adds code to check that the user isn't attempting to rename
an existing node with the name of another existing node.  Previous to
this change, such rename operations would succeed and would corrupt node
configuration data.

[FIXED JENKINS-31954] Stack overflow reconfiguring some settings where Descriptor.newInstance is gratuitously overridden.

online-node covered by test-cases

This caused a NullPointerException since newInstance was then called reëntrantly.
Adjusting NewInstanceBindInterceptor.processed handling to behave correctly in this case.

NodePropertyTest.invisibleProperty demonstrates that the fallback for onConvert must be onConvert, not instantiate, of the delegate.

The failure was in ClassLoader.checkCerts that throws the following
exception:

    if (pcerts != null && !compareCerts(pcerts, certs)) {
        throw new SecurityException("class \""+ name +
             "\"'s signer information does not match signer information of other classes in the same package");
    }

(cherry picked from commit aec2d8af)

(cherry picked from commit 7fdb5891)

(cherry picked from commit 04a874ac)