Process doesn't exit automatically when using groth16.fullProve() method -> issue for testing and custom project CLIs

[Shigoto-dev19]

Using "snarkjs" package leaves open MessagePorts due to Multi-threading in general. This issue perturbates tests as well as any project-specific cli commands that integrate proof generation.

• the process doesn't exit automatically.
• if done manually, mocha tests don't run as expected
• CLI commands run but need "^C" to exit which makes it annoying for the user and not possible to run consecutive commands.
  

[phated]

Duplicate of #152 - this is by design. Terminate the curves that are attached to the globalThis.