Import `transformers/analytical_decompositions/*` methods in `optimizers/*` (#4813)
Import `transformers/analytical_decompositions/*` methods in `optimizers/*` (#4813)

After the recent migration of decompositions from `optimizers/*` to `transformers/analytical_decompositions/*`, the following user code breaks despite deprecating the moved submodules. 

```python
from cirq import optimizers
from cirq.optimizers import two_qubit_decompositions
_ = two_qubit_decompositions.two_qubit_matrix_to_operations(mat) # This is deprecated correctly and will emit a deprecation warning but work as expected.
_ = optimizers.two_qubit_matrix_to_operations(mat) # This would currently break since the optimizers module is neither deprecated nor has these top-level objects available
```

This PR adds a fix to temporarily unbreak the above user code by importing top-level objects from `transformers/analytical_decompositions/*` to `optimizers/*`. Once all files from `optimizers/*` have been moved to `transformers/`, we will deprecate the `optimizers/` module, and then this hack can be reverted and the correct deprecation warnings will be emitted when using `optimizers.two_qubit_matrix_to_operations` (and other top-level objects). 

Part of #4722 
quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq