Support using paddle in safe_open

[zeroRains]

Support using paddle in safe_open API

This PR allows us to use safe_open API when set the framework='pp' or framework='paddle'. It just like the following code:

from safetensors import safe_open

tensors = {}
with safe_open(filename, framework="pp") as f:
    for k in f.keys():
        tensors[k] = f.get_tensor(k)

In this PR, I use the latest feature(MmapStorage) in paddle. It only support for paddle >= 3.1.0 or develop version.

We also can use the original way to load tensor if the paddle version is lower than 3.1.0.

ps: MmapStorage still a PR PaddlePaddle/Paddle#73820. It will be merged in develop and 3.1.0 branch later.

[yuanlehome]

LGTM，We hope that official classmates can help review and promote code integration. Thanks!