History is its own workspace, extracted together with a renderer

CommandDocument, ChangeReceipts and CommandHistory lived in @jolly-pixel/network/client but imported nothing from network besides each other and @openally/emitt. They moved to @jolly-pixel/history. Network depends on it for DocumentSyncClient and re-exports nothing, so consumers import history from @jolly-pixel/history.

The move was made only together with a renderer migration. The renderers cannot depend on network, so before the move pixel-draw kept History, HistoryStack and EditRecorder, pixel-art kept a ReplayBasis, and voxel-renderer kept VoxelHistory: four undo implementations with different answers to peer edits and server refusals. pixel-draw moved first, voxel-renderer next.

Considered Options

• Keep history in network. Right as long as only network documents undo.
• Re-export from network for one release. Two import paths for one class, for packages that all live in this repository.

Consequences

• One undo model: per-key guards, server refusals reported, replays sent with a basis.
• voxel-model records model and texture edits in one history.