We retain a few tests on the RunBuild plan, with `typescript` set to
false in the runtime options, but for the general case, we remove the
build steps and custom entry points for our programs.
These changes introduce a new field, `Raw`, to `diag.Message`. This
field indicates that the contents of the message are not a format string
and should not be rendered via `Sprintf` during stringification.
The plugin std{out,err} readers have been updated to use raw messages,
and the event reader in `pulumi` has been fixed s.t. it does not format
event payloads before display.
Fixes#551.