feat(btree): Add BTree global index reader with async on-demand block loading (#229)

Implement BTree index file format support (block, footer, meta, SST file,
var_len encoding) and global index scanner for evaluating predicates against
BTree global indexes to produce row ID ranges.

Key features:
- Async on-demand data block reading via FileRead trait instead of loading
  entire file into memory
- Scanner-level BTreeIndexReader cache for reader reuse across evaluations
- AND predicate grouping by field_id to minimize file opens
- Between pattern detection (GtEq/Gt + LtEq/Lt merged into single range_query)
- Row ID predicate extraction from data predicates into row ranges
- Support for point lookup, range, IN, NOT IN, IS NULL, IS NOT NULL queries
- Zstd block compression/decompression support
- File-level pruning using BTreeIndexMeta (first_key, last_key, has_nulls)

Author: JingsongLi

crates/paimon/Cargo.toml

@@ -55,6 +55,8 @@ pretty_assertions = "1"
 serde_avro_fast = { version = "2.0.2", features = ["snappy", "zstandard"] }
 indexmap = "2.5.0"
 roaring = "0.11"
+crc32fast = "1"
+zstd = "0.13"
 arrow-array = { workspace = true }
 arrow-buffer = { workspace = true }
 arrow-cast = { workspace = true }