[HealthChecks] Add ScriptHost and WebHost IHealthCheck

[jviau]

Health check service is not yet connected.

Issue describing the changes in this PR

Part of #11010 , #11169

Pull request checklist

IMPORTANT: Currently, changes must be backported to the in-proc branch to be included in Core Tools and non-Flex deployments.

• Backporting to the in-proc branch is not required
  • Otherwise: Link to backporting PR
• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• My changes do not require diagnostic events changes
  • Otherwise: I have added/updated all related diagnostic events and their documentation (Documentation issue linked to PR)
• I have added all required tests (Unit tests, E2E tests)

Additional information

Adds the implementations for WebHost and ScriptHost health checks. The health check service is not yet connected so these do nothing as of yet. I am intentionally not updating release notes as this PR on its own has no customer impact.