[mlir][bufferize][NFC] Rename DialectAnalysisState and move to OneShotAnalysis

`DialectAnalysisState` is now `OneShotAnalysisState::Extension`.

This state extension mechanism is needed only for One-Shot Analysis, so it is moved from `BufferizableOpInterface.h` to `OneShotAnalysis.h`.

Extensions are now identified via TypeIDs instead of StringRefs. The API of state extensions is cleaned up and follows the same pattern as other extension mechanisms in MLIR (e.g., `transform::TransformState::Extension`).

Also delete some dead code.

Differential Revision: https://reviews.llvm.org/D135051