Distinguish between the project name and Macroni dialect name

[PappasBrent]

The project is currently named Macroni.
This is for two reasons:

1. When the project was first started, the plan was to create a single dialect for lowering as many macros as possible down to MLIR.
2. All the project's executables depended on PASTA, so "Macroni" was a clever pun.

The first point no longer applies since we now offer more dialects (currently the Kernel dialect for analyzing RCU macro invocations, and the simple Safety dialect which is really more of a proof-of-concept for using MLIR+macros to add new language features to C).
Moreover, once #21 is completed only the Macroni dialect will depend on PASTA, and so the second reason for naming the project Macroni will not hold either.
Therefore I think it would be better to rename the project to something that has to do more with the general idea of lowering macros to MLIR, and reserving the Macroni name for the Macroni dialect only, since that is the only dialect which uses PASTA.

This will at least require renaming many CMake targets, C++ namespaces, and the GitHub project.
However it will help us finally distinguish between the project as a whole and the Macroni dialect specifically.