MySql.AddDatabase creates database for resource

[RussKie]

Resolves #8294

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue (consider using one of the following templates):
      • New (or update) doc-idea template
      • New breaking-change template
      • New diagnostic template
  • No

[Copilot]

Pull Request Overview

This PR adds support for creating MySQL databases via the AddDatabase API, including the ability to specify custom creation scripts. Key changes include:

• New functional tests demonstrating database creation with and without a custom script.
• Updates to MySqlServerResource and MySqlDatabaseResource for improved database resource management and connection string construction.
• Enhancements to MySqlBuilderExtensions for handling resource events and creating databases upon resource readiness.

Reviewed Changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/Aspire.Hosting.MySql.Tests/MySqlFunctionalTests.cs	Added tests for AddDatabase functionality with regular and custom scripts
src/Aspire.Hosting.MySql/MySqlServerResource.cs	Updated to track database resources with new properties
src/Aspire.Hosting.MySql/MySqlDatabaseResource.cs	Revised connection string property using MySqlConnectionStringBuilder
src/Aspire.Hosting.MySql/MySqlCreateDatabaseScriptAnnotation.cs	Introduced annotation class for custom database creation scripts
src/Aspire.Hosting.MySql/MySqlBuilderExtensions.cs	Added event subscriptions and database creation logic based on resource readiness
playground/mysql/MySqlDb.AppHost/Program.cs	Adjusted setup to include multiple databases, including one with a custom script
playground/mysql/MySql.ApiService/Program.cs	Added keyed MySQL data source and an endpoint to query data from the custom script database

Files not reviewed (1)

• playground/mysql/MySql.ApiService/MySql.ApiService.http: Language not supported

[RussKie]

I pretty much copied the changeset from #8022, #8086 and #8085.

[sebastienros]

Note that very soon we may want to change how these scripts to use the init scripts support provided by each container instead of invoking these with ADO.NET. But it should not matter for this PR right now.