feat(prover): Add file based config for fri prover gateway (#2150)

## What ❔

Add file based config for fri prover gateway

## Checklist

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- [x] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [x] Tests for the changes have been added / updated.
- [x] Documentation comments have been added / updated.
- [x] Code has been formatted via `zk fmt` and `zk lint`.
- [x] Spellcheck has been run via `zk spellcheck`.

core/lib/zksync_core_leftovers/src/temp_config_store/mod.rs

@@ -32,7 +32,7 @@ pub fn decode_yaml_repr<T: ProtoRepr>(yaml: &str) -> anyhow::Result<T::Type> {
 // TODO (QIT-22): This structure is going to be removed when components will be responsible for their own configs.
 /// A temporary config store allowing to pass deserialized configs from `zksync_server` to `zksync_core`.
 /// All the configs are optional, since for some component combination it is not needed to pass all the configs.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Default)]
 pub struct TempConfigStore {
     pub postgres_config: Option<PostgresConfig>,
     pub health_check_config: Option<HealthCheckConfig>,