This change moves us away from using JavaScript RTTI, by way of
`instanceof`, for built-in Pulumi types. If we use `instanceof`,
then the same logical type loaded from separate copies of the
SDK package -- as will happen in SxS scenarios -- are considered
different. This isn't actually what we want. The solution is
simple: implement our own quasi-RTTI solution, using __pulumi*
properties and manual as* and is* functions. Note that we could
have skipped the as* and is* functions, but I found that they led
to slightly easier to read code.
There is one strange thing in here, which I spoke to
@CyrusNajmabadi about: SerializedOutput<T>, because it implements
Output<T> as an _interface_, did not previously masquerade as an
actual Output<T>. In other words, `instanceof` would have returned
false, and indeed a few important properties (like promise) are
missing. This change preserves that behavior, although I'll admit
that this is slightly odd. I suspect we'll want to revisit this as
part of https://github.com/pulumi/pulumi/issues/1074.
Fixes https://github.com/pulumi/pulumi/issues/1203.
6f4423895c