Estimating Noise Budget without Secret Key

In the latest version of SEAL, the Simulation class has been removed.
Has it been shifted to some other file?
If it has been completely removed from the library, then how can I estimate noise growth, and choose appropriate parameters for my application?

Simulation class and related tools are indeed removed from the most recent SEAL. There were several reasons for this:

• updating them was simply too much work with all the recent API changes;
• the parameter selection and noise growth estimation tools worked well only in extremely restricted settings, e.g. very shallow computations;
• the design of these tools didn't necessary correspond very well to how we envision parameter selection to happen in the future.

Obviously it's really important to have developer tools in SEAL (e.g. parameter selection, circuit analysis/optimization, etc.) so these will surely be coming back in some form.

Even without explicit tools for parameter selection you can still test different parameters and see how much noise budget you have left after the computation. Repeat this experiment multiple times to account for probabilistic effects and convince yourself that the parameters indeed work.