Lucet-runtime support for statically linked lucetc output

[pchickey]

Currently, lucet-runtime uses dlopen and dlsym in the DlModule struct to look up symbols in the lucetc-generated object file.

In order for static linking to work, we need to use lucet-module-data to access all aspects of a compiled module. This includes mapping export function names (as strings) to code pointers.

lucet-module-data will have to include a serialization of code pointers. Serde doesn't support this, so we'll have to serialize it directly with faerie and deserialize it with hand-written unsafe rust.

Hopefully, this same underlying representation will be usable by MockModule, DlModule, and StaticModule, so that most of the difficult code lives in the Module trait, and the three different representations are as simple as possible.

Depends on #20

[pchickey]

We are not developing new features in lucet anymore