Rename aztec-gddt to something else

[danlessa]

We should decide a more relatable name for what this simulation product is about

[jackhack00]

Aztec Labs has previously suggested "SimNet", which works a bit more nicely with testnet / mainnet etc nomenclature.
I am unsure if that's ideal though, as we are not necessarily doing a "network" of models.
In our current report I've punted this slightly by saying "our ongoing simulation efforts".
Happy for any naming suggestions!