Ensure wwwroot directory exists on new slot and app creation w/ networking restrictions

[satvu]

Issue describing the changes in this PR

resolves #11654

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)

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Ensures the worker process working directory is created when missing (e.g., new deployment slots/apps) and adds a unit test to cover the behavior.

Changes:

• Create the worker process working directory on demand before building the ProcessStartInfo.
• Add a unit test validating the working directory is created and applied to the worker ProcessStartInfo.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
test/WebJobs.Script.Tests/Workers/DefaultWorkerProcessFactoryTests.cs	Adds a unit test validating missing working directories are created and used.
src/WebJobs.Script.Grpc/ProcessManagement/DefaultWorkerProcessFactory.cs	Creates the working directory if it doesn’t exist before creating the worker process.

[Copilot]

If directory creation fails, the method continues and will likely fail later when starting the process with a non-existent WorkingDirectory, producing a less actionable error. Consider failing fast by rethrowing (or throwing a dedicated exception), or explicitly clearing/falling back the working directory when creation fails so the process can still start deterministically.

Suggested change

	_logger.LogWarning(ex, "Failed to create working directory '{workingDirectory}'. The worker process may fail to start.", context.WorkingDirectory);
	_logger.LogWarning(ex, "Failed to create working directory '{workingDirectory}'.", context.WorkingDirectory);
	throw new InvalidOperationException($"Failed to create working directory '{context.WorkingDirectory}' for the worker process.", ex);

[satvu]

I think the current failure behavior (diagnostic error saying no directory is found) is sufficient and this log adds more information upon investigation.