✨ Allow external RNG

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Suggestion

as a consumer of electionguard i would like to be able to provide my own random number generator instead of relying o nthe internal one when encrypting ballots so that i can use my own source of entropy and dont have to rely on the internal electionguard implementation

### Possible Implementation

abstract random number generation to our own domain-specific interfaces and protocols and provide a default implementation using our existing random number generator. Add it to the ballot encryption interface and anywhere else a random number generator is used. expose it through c/c#.

### Anything else?

_No response_