SI-6082 Conditionally expand @ann(x) to @ann(value = x)

... if the annotation has an argument with the name `value`.

Doing so unconditionally obscures error messages.

We still require that arguments to ClassFileAnnotations
are named, other than for this special case.
Merge pull request #1894 from retronym/ticket/6082

SI-6082 Conditionally expand @ann(x) to @ann(value = x)