Finds the adapter that links against the compiler on this class path.

Selection is by linkage, not by version string. Instantiating an adapter forces the JVM to resolve the compiler types it binds to, so an adapter written for an AST this compiler does not have fails here, in a controlled place, instead of part-way through a measurement. A fork reporting an unfamiliar version may still link; a compiler reporting a familiar one may not. The JVM knows, and it is cheaper to ask it than to maintain a table of which versions are secretly compatible.

Loaded by name so that nothing outside this method mentions an adapter class. The phase that runs without a compiler on its class path can hold a reference to CompilerModel all day; it never loads anything that would need Scala or Flix to resolve.