feat: introduce basic data types including decimal, blob and timestamp

[lszskye]

Purpose

Introduce the basic data types module including:

• Decimal: A 128-bit decimal type compatible with Java Paimon's DecimalData.
• Blob: A binary large object type that supports reading from file paths or blob descriptors.
• Timestamp: An immutable timestamp type representing milliseconds + nanos-of-millisecond since epoch.
• Logger: A pluggable logging framework with a default glog-based adapter, supporting custom logger registration and thread-safe initialization.

Internal utilities added:

• BlobDescriptor: Serializable descriptor for blob references with versioned binary format (v1/v2 compatible with Java).
• BlobDefs: Constants for blob file format (magic number, header layout, etc.).
• BlobUtils: Helper functions for separating blob/non-blob fields in Arrow schemas and arrays.

Tests

• BlobTest
• BlobDescriptorTest
• BlobUtilsTest
• DecimalTest
• TimestampTest
• LoggerTest

API and Format

This change adds new public headers under include/paimon/data/:

• blob.h — Blob class
• decimal.h — Decimal class
• timestamp.h — Timestamp class

And extends include/paimon/logging.h with the Logger interface.

No existing API or storage format is changed.

[leaves12138]

Thanks for migrating the basic data types and logging utilities. I compared the added files with the source snapshot; they match the staged migration with ASF header normalization. The PR is based on the current main and merges cleanly. I also checked line endings/trailing whitespace and ran a lightweight public-header syntax smoke check; no blocker found.

Non-blocking note: some implementation/test files still depend on components expected to arrive in later migration PRs, such as filesystem, IO streams, string/decimal utilities, and executor futures. That looks fine for the staged migration.

LGTM.