[FEA] Make the rmm._cuda.stream.Stream a part of the public API

[Matt711]

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I wish I could use RMM to do [...]
We're starting to expose streams to pylibcudf APIs. xref rapidsai/cudf#15163 and rapidsai/cudf#17620). Can we make Stream part of the public API.

Describe the solution you'd like
Migrate rmm._cuda.stream.Stream to rmm.pylibrmm.stream.Stream. We would deprecate rmm._cuda.stream.Stream for 25.02 and remove it in 25.04.

[vyasr]

cuda-python is proposing a __cuda_stream__ protocol that any stream type could implement to support interoperability. I would suggest that we basically both implement that protocol and accept any object supporting that protocol. Concretely, I would replace the current stream constructor with something like the following:

cdef class Stream:
    def __init__(self, obj=None):
        self._init_from_stream(obj)

    @singledispatchmethod
    def _init_from_stream(self, stream):
        try:
            protocol = getattr(obj, "__cuda_stream__")
        except AttributeError:
            raise ValueError(
                "stream must be a supported stream type or implement the __cuda_stream__ protocol"
            )
        if protocol[0] != 0:
            raise ValueError("Only protocol version 0 is supported")
                                                                                 
        self._cuda_stream = stream
        self.owner = stream

    @_from_stream.register()
    def _from_stream(self, Stream):
        self._cuda_stream, self._owner = stream._cuda_stream, stream._owner
                                                                                                                                             
    @_from_stream.register()                                                                                        
    def _from_stream(self, stream: numba.cuda.cudadrv.driver.Stream):
        # Whatever special handling for numba if needed, but ideally could just use the protocol