feat: CON-1445 Helper functions to create NiDkgConfigs from request contexts

[eichhorl]

Previously, configs for Remote DKG requests were only created and included as part of summary blocks. This implies that a request has to wait until the end of the current interval to even be started.

This PR introduces two new functions that will be used to start working on remote DKG requests as soon as they appear in the replicated state.

build_callback_id_config_map

This function iterates over all remote DKG request contexts and attempts to derive the corresponding DKG configs. This is done by using the start height of the most recent summary block. In case of malformed inputs, errors are returned instead.

One special aspect is the use of the initial_dkg_attempts map, which is maintained by the summary payload. Entries of this map are incremented whenever there is still an outstanding request context in the replicated state, when the summary block is created. If the number of attempts exceeds the maximum, the new function will generate a timeout error instead. Furthermore, we will use this map to track remote DKG requests that have been completed as part of the previous interval. Target IDs for such requests will be inserted into this map with a count of 0. This ensures that they will not be attempted again in the subsequent interval.

merge_configs

This function takes configs from the recent summary, and merges them with configs derived from the latest state using build_callback_id_config_map. The output represents the combined set of configs for currently ongoing DKGs.

Note that the new functions are still unused.

[Copilot]

Pull request overview

This PR introduces an (currently unused) internal module to derive remote NiDKG configs directly from replicated-state request contexts, enabling remote DKG work to begin before the next summary block is produced.

Changes:

• Added build_callback_id_config_map to derive per-callback remote DKG config results from ReplicatedState and the latest DkgSummary, including timeout handling via initial_dkg_attempts.
• Added merge_configs to combine summary-derived configs with context-derived configs (successes only).
• Refactored create_remote_dkg_config_for_key_id to accept a transcript lookup function and widened visibility of a few helper functions for reuse.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
rs/consensus/dkg/src/remote.rs	New module with remote-context→config derivation + merge helper and unit tests.
rs/consensus/dkg/src/payload_builder.rs	Adjusted remote config creation API (closure-based transcript lookup) and made helper functions pub(crate) for reuse.
rs/consensus/dkg/src/lib.rs	Added remote module to the crate with a module-level #[allow(dead_code)].

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