feat: support more runtimes rather than tokio

[MrCroxx]

https://tonbo.io/ develops a portable embedded database without tokio support. They want to try foyer in their environment, which requires foyer to run with general runtime rather than tokio only.

[MrCroxx]

@ethe Would you like to describe the details of your requirements? 🙌

[ethe]

Sure, thanks @MrCroxx , in the current, we are trying to use foyer in tonbo: https://github.com/tonbo-io/tonbo/pull/193/files#diff-576a25b15b009b660e408a738b04427884b18a77372406660bc3cf682486a4a1R11 . However, foyer is locked in tokio: https://github.com/foyer-rs/foyer/blob/main/Cargo.toml#L41 . Considering the scenarios Tonbo plans to support: WASM, Python, are there any plans to remove the requirement of Tokio?