feat: introduce Result Service using Lakekeeper as REST catalog for Iceberg

[mengw15]

What changes were proposed in this PR?

This PR introduces Lakekeeper as a REST catalog service for Iceberg, replacing direct JDBC catalog connections. Key changes include:

• Lakekeeper bootstrap script (bin/bootstrap-lakekeeper.sh): automates Lakekeeper setup with MinIO as the S3-compatible storage backend.
• Iceberg catalog migration (Scala & Python): updated Scala side and Python side to connect via the Lakekeeper REST catalog instead of direct JDBC.
• Single-node deployment: updated bin/single-node/docker-compose.yml to include Lakekeeper and MinIO services.
• Kubernetes deployment: added Lakekeeper init job, external-names for service discovery, and exposed Lakekeeper to the computing-unit pool.

Post-merge setup for developers

After this PR is merged, each developer needs to perform the following one-time setup:

1. Create the Lakekeeper database

psql -f sql/texera_lakekeeper.sql

2. Download the Lakekeeper binary

Go to the Lakekeeper releases page and download the binary for your platform
Place it somewhere on your machine

3. Configure bin/bootstrap-lakekeeper.sh

Edit the User Configuration section at the top of the script:

LAKEKEEPER_BINARY_PATH — path to the downloaded Lakekeeper binary
LAKEKEEPER__PG_DATABASE_URL_READ / LAKEKEEPER__PG_DATABASE_URL_WRITE — PostgreSQL connection URL in the format postgres://username:password@hostname:5432/texera_lakekeeper

4. Run the bootstrap script

./bin/bootstrap-lakekeeper.sh
This will start Lakekeeper, create the default project, set up the MinIO bucket, and create the warehouse.

Any related issues, documentation, discussions?

Closes #4126

How was this PR tested?

Tested manually on single-node Docker Compose deployment and Kubernetes cluster

Was this PR authored or co-authored using generative AI tooling?

co-authored with AI

[mengw15]

@bobbai00