Release Apache Iceberg C++ 0.4.0

[manuzhang]

• Test the revision to be released
• Bump version to 0.4.0
• Prepare RC and create tag by running dev/release/release_rc.sh
• Verify RC by running dev/release/verify_rc.sh
• Send vote email
• Publish release after the vote passes by running dev/release/release.sh
• Report to ASF: https://reporter.apache.org/addrelease.html?iceberg
• Write release blog
• Send announcement email
• Bump version to 0.5.0-SNAPSHOT

For details of each step, please refer to https://github.com/apache/iceberg-cpp/tree/main/dev/release.

[manuzhang]

0.4.0 rc0 has been created and sent to dev list for vote