feat: add cache manager functionality

[matthewhaynesonline]

Depends on #143

Motivation

Begins the work of providing cache management features in the Rust client and providing parity with the Python client huggingface_hub/utils/_cache_manager.py. (which would be useful for a pet project I'm going to work on).

Summary

• Port cache scanning and deletion strategy from python client _cache_manager.py
• Add cache-manager feature flag for core functionality
• Add cache-manager-display feature flag for table output
• Add cache-manager example with usage docs

Note: there are some difference from the python implementation where it made sense from a rust perspective, but I tried to be faithful to the original.

$ cargo run --example cache-manager --features="cache-manager"

    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.07s
     Running `target/debug/examples/cache-manager`
[examples/cache-manager.rs:16:5] &cache_info = HFCacheInfo {
    size_on_disk: 76178327175,
    repos: {
        CachedRepoInfo {
            repo: Repo {
                repo_id: "HuggingFaceTB/SmolLM2-1.7B-Instruct",
                repo_type: Model,
                revision: "main",
            },
            repo_path: "/Users/matt/.cache/huggingface/hub/models--HuggingFaceTB--SmolLM2-1.7B-Instruct",
            size_on_disk: 3426154904,
            nb_files: 8,
            revisions: {
               ...
            },
            last_accessed: Some(
                SystemTime {
                    tv_sec: 1738021666,
                    tv_nsec: 353517867,
                },
            ),
            last_modified: Some(
                SystemTime {
                    tv_sec: 1737955174,
                    tv_nsec: 621743227,
                },
            ),
        },
        ...
    },
    warnings: [
        RepoNotDir {
            ...
        },
        
        InvalidRepoName {
            ...
        },
    ],
    cache: Cache {
        path: "/Users/matt/.cache/huggingface/hub",
    },
}

$ cargo run --example cache-manager --features="cache-manager" -- e8c3b32edf5434bc2275fc9bab85f82640a19130
   
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.23s
     Running `target/debug/examples/cache-manager e8c3b32edf5434bc2275fc9bab85f82640a19130`
...
[examples/cache-manager.rs:16:5] &cache_info = HFCacheInfo {
    size_on_disk: 76178327175,
    repos: {...}
}

[examples/cache-manager.rs:21:9] &delete_strat = DeleteCacheStrategy {
    expected_freed_size: 438682922,
    blobs: {},
    refs: {},
    repos: {
        "/Users/matt/.cache/huggingface/hub/models--sentence-transformers--all-mpnet-base-v2",
    },
    snapshots: {},
}

$ cargo run --example cache-manager --features="cache-manager,cache-manager-display"

   Compiling hf-hub v0.5.0 (/Users/matt/Code/matthewhaynes/hf-hub)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.38s
     Running `target/debug/examples/cache-manager`
     
+-------------------------------------------------+-----------+--------------+----------+---------------+---------------+------------------+---------------------------------------------------------------------------------------------+
| REPO ID                                         | REPO TYPE | SIZE ON DISK | NB FILES | LAST_ACCESSED | LAST_MODIFIED | REFS             | LOCAL PATH                                                                                  |
+========================================================================================================================================================================================================================================+
|-------------------------------------------------+-----------+--------------+----------+---------------+---------------+------------------+---------------------------------------------------------------------------------------------|
| HuggingFaceTB/SmolLM2-1.7B-Instruct             | model     |         3.4G | 8        | 1 year ago    | 1 year ago    | main             | /Users/matt/.cache/huggingface/hub/models--HuggingFaceTB--SmolLM2-1.7B-Instruct             |
|-------------------------------------------------+-----------+--------------+----------+---------------+---------------+------------------+---------------------------------------------------------------------------------------------|
...
|-------------------------------------------------+-----------+--------------+----------+---------------+---------------+------------------+---------------------------------------------------------------------------------------------|
| sentence-transformers/all-mpnet-base-v2         | model     |       438.7M | 11       | 2 days ago    | 6 days ago    | main             | /Users/matt/.cache/huggingface/hub/models--sentence-transformers--all-mpnet-base-v2         |
+-------------------------------------------------+-----------+--------------+----------+---------------+---------------+------------------+---------------------------------------------------------------------------------------------+%