feat: let crate ckb-hash support no-std

[yangby-cryptape]

What problem does this PR solve?

Let ckb-hash support no-std, so developers don't have to copy constants again and again when write CKB contracts with Rust, such as CKB_HASH_PERSONALIZATION, to avoid typos.

For examples:

• axonweb3/ckb-type-id
• synapseweb3/ibc-ckb-contracts

What is changed and how it works?

Both blake2b-rs (when cfg(not(target_arch = "wasm32"))) and blake2b-ref (when cfg(target_arch = "wasm32")) are support no-std with default features.

So, just adding #![no_std] is enough.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code ci-runs-only: [ quick_checks,linters ]

Release note

Title Only: Include only the PR title in the release note.