Added overload of AddConnectionString using the builder pattern to make it more approachable

[davidfowl]

Description

Added overload of AddConnectionString using the builder pattern to make it more approachable

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
• 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
    • Is this introducing a breaking change?
      • Yes
        • Link to aspire-docs issue (please use this breaking-change template):
      • No
        • Link to aspire-docs issue (please use this doc-idea template):
  • No

[Copilot]

Pull Request Overview

This PR adds an overload for AddConnectionString that leverages the builder pattern, making the API more approachable for constructing connection strings.

• Introduces a new overload method with appropriate XML documentation and example code.
• Updates the test suite to reflect the new API and corrects a typo in a test method name.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/Aspire.Hosting/ConnectionStringBuilderExtensions.cs	Adds the overload and XML comments using the builder pattern to construct connection strings.
tests/Aspire.Hosting.Tests/WithReferenceTests.cs	Fixes a test method name typo and introduces a new test for the builder overload.