cardano-testnet | Extract EpochStateView into its own module
Move EpochStateView, its background-thread setup, the STM-based wait primitive, and the retry loops out of Testnet.Components.Query and into a new module Testnet.Components.EpochStateView. The new module carries a top-down haddock that explains how the writer thread, the version counter, and awaitStateUpdateTimeout cooperate so that future readers can learn the mechanism from one place rather than piecing it together across Query.hs. Testnet.Components.Query re-exports the public API so existing callers do not need to change their imports.