[mlir][bufferization][transform][python] Add enums to bindings & mixins.

This patch uses the new enum binding generation to add the enums of the
dialect to the Python bindings and uses them in the mix-in class where
it was still missing (namely, the `LayoutMapOption` for the
`function_boundary_type_conversion` of the `OneShotBufferizeOp`.

The patch also piggy-backs a few smaller clean-ups:
* Order the keyword-only arguments alphabetically.
* Add the keyword-only arguments to an overload where they were left out
  by accident.
* Change some of the attribute values used in the tests to non-default
  values such that they show up in the output IR and check for that
  output.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D156664