add database example

[johnoliver]

Motivation and Context

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[Copilot]

Pull Request Overview

This PR adds a comprehensive database sample demonstrating how to use Semantic Kernel with MySQL database for vector storage operations. The sample includes vector search functionality using OpenAI embeddings and shows how to store and retrieve GitHub file information.

Key changes:

• Complete MySQL database sample with Docker setup and vector operations
• Cleanup of reactor-core dependency from semantickernel-api-data and moved to data-jdbc module
• Minor Docker case standardization fix for presidio sample

Reviewed Changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
samples/semantickernel-demos/sk-database-sample/*	New complete database sample with Maven project, Docker setup, and vector storage demonstration
semantickernel-api-data/pom.xml	Removes reactor-core dependency that was likely moved to appropriate module
data/semantickernel-data-jdbc/pom.xml	Adds reactor-core dependency to the JDBC data module where it's actually needed
samples/semantickernel-demos/pom.xml	Adds new database sample module to parent POM
samples/semantickernel-demos/sk-presidio-sample/sk-presidio-sample-dockerfile	Standardizes Docker FROM statement case

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[karianna]

Will have to review this properly later on

[karianna]

There's a newer wrapper version IIRC