Create utilities for examples

[mattnite]

We have enough examples in MicroZig, we should have utilities for grouping targets, programs, a naming standard, and filtering that can be used across all the example build scripts.

[tact1m4n3]

What do you think of a simple directory structure inside zig-out/firmware (like one directory per target)? There are a lot of elfs and uf2s in the output dir for a port like rp2xxx also because of the fact that there are multiple targets per example. For me this isn't an issue, I don't mind the status quo.