* Also fixes bug in JITCompiler when first output of inner fgraph is an input variable, as can happen in some specific functions with updates

Otherwise TestSharedOptions.test_specify_shape_inplace would fail

`ChoiceRV` currently does not behave like its NumPy equivalent when its
`a` parameters is an `int` or an array with more than one dimension. We
implement the necessary changes so that it does.