Find a way to connect HEIR parameters to API parameter settings

Right now when `heir-translate` emits code for OpenFHE and tfhe-rs, the parameters expressed in the HEIR IR are ignored in the generated code.

E.g., in [binops.mlir](
https://github.com/google/heir/blob/main/tests/openfhe/end_to_end/binops.mlir), I have set arbitrarily

```
#encoding = #lwe.polynomial_evaluation_encoding
#params = #lwe.rlwe_params
```

And the generated code has none of these values. Instead the test writer must manually set parameters as in [binops_test.cpp](https://github.com/google/heir/blob/main/tests/openfhe/end_to_end/binops_test.cpp#L27-L32).

For tests this is merely annoying, but for real production use cases we will need a way for the compiler to emit code that the client and server can use to configure their "CryptoContext" objects (or similar for other library backends) so that they use the right parameters.