Log executor metrics only if enabled in config

[rafal-ch]

Draft attempt to use "metrics" config param in the executor.

Not sure if this is the way to go because it adds metrics field to ExecutionOptions, which in turn is a member of the versioned InputSerializationType and InputDeserializationType. This could mean a breaking change.

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Alternative approach would be to log the metrics in higher layer, ie.: modify the fn produce_inner<TxSource>() to get additional metrics parameter (we have access to Config in all call-sites). Then after either of native_produce_inner() or wasm_produce_inner() finishes, the metric values could be calculated from the ExecutionResult.

[rafal-ch]

Not doing this, will update the metrics in the importer.