Containers and config for non-validating staked builders

[StefanBratanov]

PR Description

Containers and config as per ethereum/consensus-specs#4788

Even though yet not merged, specs have been more or less approved, so I don't expect changes in the structures, so it's a good start to prepare for this change.

Specrefs CI is supposed to fail, will fix after new release of consensus-specs

Fixed Issue(s)

N/A

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

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Note

Adds non-validating builder support to the Gloas fork with new state fields, SSZ containers, and configuration.

• New SSZ types in state.versions.gloas: Builder, BuilderPendingPayment, BuilderPendingWithdrawal; update schema registry, accessors, and tests (moved from epbs.*)
• Extend BeaconStateGloas schema with builders and next_withdrawal_builder_index; add getters/setters, toString description, state upgrade initialization, and builder/test utilities
• Config: add BUILDER_REGISTRY_LIMIT, MAX_BUILDERS_PER_WITHDRAWALS_SWEEP, MIN_BUILDER_WITHDRAWABILITY_DELAY; expose via SpecConfigGloas/DelegatingSpecConfigGloas and GloasBuilder; minor util fix for default Long
• Update network presets (gloas.yaml in mainnet/minimal/gnosis/swift) and exported mainnetConfig.json
• REST API: update BeaconStateGloas.json to include builders and next_withdrawal_builder_index; add Builder.json schema
• Minor logic/usage updates and tests to align with new constants and types

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