fix: embed_external_files=True for mesh support

[Vinay-Umrethe]

Fix for #8055

This is follow-up PR for fixing a specific issue related to dataset.push_to_hub(repo_id, embed_external_files=True)

Test Conducted

from datasets import Features, Image, Mesh, Value, load_dataset


repo_id = "VINAY-UMRETHE/My-Mesh-Dataset"

dataset = load_dataset("json", data_files="TEST_DATA/records.jsonl", split="train")
dataset = dataset.map(
    lambda example: {
        "image": "TEST_DATA/" + example["image_path"],
        "mesh": "TEST_DATA/" + example["mesh_path"],
    }
)
dataset = dataset.cast(
    Features(
        {
            "id": Value("string"),
            "text": Value("string"),
            "image_path": Value("string"),
            "mesh_path": Value("string"),
            "image": Image(),
            "mesh": Mesh(),
        }
    )
)

dataset.push_to_hub(repo_id, embed_external_files=True)

Demo: VINAY-UMRETHE/My-Mesh-Dataset