feat(core): add CellAny

It's definitely a mistake to name `CellOnChain` `Cell`, but there is nothing we can do with that right now. To avoid more duplicate code, `CellAny` was added to represent a cell that's on-chain or off-chain.

Author: Hanssen0

.changeset/salty-apples-check.md

@@ -0,0 +1,9 @@
+---
+"@ckb-ccc/core": minor
+"@ckb-ccc/ssri": patch
+---
+
+feat(core): add `CellAny`
+
+It's definitely a mistake to name `CellOnChain` `Cell`, but there is nothing we can do with that right now. To avoid more duplicate code, `CellAny` was added to represent a cell that's on-chain or off-chain.
+