feat(sql): decode binary output formats

[sundy-li]

Summary

• decode Binary values according to BinaryFormat: HEX, BASE64, UTF-8, and UTF-8-LOSSY
• apply the configured format to top-level and nested Binary values
• preserve Map key/value boundaries, including : separators for Binary keys
• add coverage for top-level formats, nested Base64 Map keys, Hex Map keys, and Nullable Binary
• replace unsafe UTF-8 conversions in the affected string decoder paths with checked conversions
• remove the obsolete Hex-only binary token helper

Related

Reimplements the useful parts of closed PR #772.

Verification

• cargo fmt --all -- --check
• cargo test -p databend-driver-core --lib
• cargo test -p databend-driver-core --all-features --lib
• cargo check -p databend-driver-core
• cargo clippy -p databend-driver-core --all-targets --all-features -- -D warnings
• git diff --check

Integration tests requiring a running Databend server were not run.