Enum should be a scalar for broadcast

[stevengj]

It seems like we need a definition

broadcastable(x::Enum) = Ref(x)

like the ones here.

Pointed out recently on discourse.

This won't break backwards compatibility, because currently broadcasting over an enum gives MethodError: no method matching length(::Foo).

[AzamatB]

Was fixed by #30675, so close this?

[pjgorski]

In Julia LTS this error still exists:

Example:

@enum E x = 0 y = 1
Es = [E(0) for i in 1:100]
Es .== E(0)

[stevengj]

This feature requires Julia 1.2 or later.