Making PathNormalizer a public class from Aspire.Hosting.Utils

[aaronpowell]

Description

When creating an integration that works with the local file system, it'd be ideal to use the PathNormalizer utility class so that custom integrations can behave consistently with Aspire "core" integrations. Currently, this class is internal and the only workaround is to copy it into your own codebase - which is not ideal.

This PR makes the class public, documents it, adds it to the unshipped API file, and removes the shared include from integrations that relied on it.

Contributes to #6807

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
    • 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

Microsoft Reviewers: Open in CodeFlow