Upserts example and examples restructuring

[alex-clickhouse]

Note

Introduces a new upsert example and cleans up example references.

• Adds Insert_007_UpsertsWithReplacingMergeTree.cs demonstrating upsert, soft delete, FINAL queries, and OPTIMIZE with ReplacingMergeTree
• Updates examples/Program.cs to run the new example
• Restructures examples/README.md to new subfolder paths and adds the new example link
• Removes obsolete ClickHouseBulkCopy.InitAsync() calls in DataTypes_005_JsonType.cs (bulk copy now initializes automatically)
• Updates RELEASENOTES.md with links to expanded documentation and usage examples

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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