Improvements to measuring Bottlerocket settings to PCR 8

**What I'd like:**

Bottlerocket measures OS settings into PCR 8 via rottweiler. It currently excludes `settings.network.hostname` and `settings.updates.seed`:

https://github.com/bottlerocket-os/bottlerocket-core-kit/blob/b76210536e1f19f8922d1fa1854c43adae7a97bd/sources/rottweiler/src/system.rs#L164-L179

I would like more control over what OS settings are measured into PCR 8 with the ultimate goal of making PCR 8 predictions viable via [pcrsys](https://github.com/bottlerocket-os/twoliter/tree/develop/tools/pcrsys).

- [ ] Add `settings.measurement.excluded-settings` to variants with the `encrypted-storage` feature enabled
- [ ] Add optional PCR prediction to `pcrsys` when provided input user data TOMl

**Any alternatives you've considered:**

Keep the status quo

Start with rottweiler's sources/rottweiler/src/system.rs around lines 164-179 to understand the current PCR 8 exclusions, then inspect the pcrsys tool and its user data TOML input. Define the measurement exclusion setting for encrypted-storage variants and optional PCR prediction; done means both requested checklist items are implemented and predictions reflect the supplied settings.

Written by the indexing model from the issue text.