Smoketests: remove interface for using a module source string; always require a precompiled module

Smoketests which use precompiled modules have better performance characteristics than those that use modules with source strings (mostly because our CI can be smarter about them), so we want to require that all smoketests use precompiled modules. Currently, we have a few smoketests which use non-precompiled modules specifically because they assert that the compilation will fail. We should rewrite those tests so that they either call spacetime build explicitly or use a separate, purpose-built abstraction, rather than calling a normal Smoketest constructor and asserting that it fails. Then, we should remove the Smoketest constructor that accepts a source string, so that all smoketests have to use precompiled modules.

首先定位接受源字符串的 Smoketest 构造函数，以及所有使用它的 smoketest。检查现有的编译失败用例，然后确认它们使用显式构建或单独的抽象，并且其余每个 Smoketest 都使用预编译模块；该构造函数不应再接受源字符串。