* crate skeleton and type definitions
* add ChainSelectionMessage
* add error type
* run loop
* fix overseer
* simplify determine_new_blocks API
* write an overlay struct and fetch new blocks
* add new function to overlay
* more flow
* add leaves to overlay and add a strong type around leaves-set
* add is_parent_viable
* implement block import, ignoring reversions
* add stagnant-at to overlay
* add stagnant
* add revert consensus log
* flow for reversions
* extract and import block reversions
* recursively update viability
* remove redundant parameter from WriteBlockEntry
* do some removal of viable leaves
* address grumbles
* refactor
* address grumbles
* add comment about non-monotonicity
* extract backend to submodule
* begin the hunt for viable leaves
* viability pivots for updating the active leaves
* remove LeafSearchFrontier
* partially -> explicitly viable and untwist some booleans
* extract tree to submodule
* implement block finality update
* Implement block approval routine
* implement stagnant detection
* ensure blocks pruned on finality are removed from the active leaves set
* write down some planned test cases
* floww
* leaf loading
* implement best_leaf_containing
* write down a few more tests to do
* remove dependence of tree on header
* guide: ChainApiMessage::BlockWeight
* node: BlockWeight ChainAPI
* fix compile issue
* note a few TODOs for the future
* fetch block weight using new BlockWeight ChainAPI
* implement unimplemented
* sort leaves by block number after weight
* remove warnings and add more TODOs
* create test module
* storage for test backend
* wrap inner in mutex
* add write waker query to test backend
* Add OverseerSignal -> FromOverseer conversion
* add test harnes
* add no-op test
* add some more test helpers
* the first test
* more progress on tests
* test two subtrees
* determine-new-blocks: cleaner genesis avoidance and tighter ancestry requests
* don't make ancestry requests when asking for one block
* add a couple more tests
* add to AllMessages in guide
* remove bad spaces from bridge
* compact iterator
* test import with gaps
* more reversion tests
* test finalization pruning subtrees
* fixups
* test clobbering and fix bug in overlay
* exhaustive backend state after finalizaiton tested
* more finality tests
* leaf tests
* test approval
* test ChainSelectionMessage::Leaves thoroughly
* remove TODO
* avoid Ordering::is_ne so CI can build
* comment algorithmic complexity
* Update node/core/chain-selection/src/lib.rs
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>
Robert Habermeier