fix(remix-dev): ensure devServerPort config value is the same across reloads

[tessellator]

Closes: #2958

• Tests

If the devServerPort changes values across config reloads then LiveReload will attempt to connect to an incorrect port. Files being created, deleted, or renamed under the app folder trigger config reloads.

Testing Strategy:

A test is included in the commit that ensures that the same devServerPort is always returned.

Additionally, I tested a new project with this code using the following steps:

1. Create a new project using create-remix@latest and replace @remix-run/dev with a build including the code in the attached commit.
2. Run npm run dev
3. Browse to localhost:3000. Verify LiveReload is working by editing app/routes/index.tsx and observing the change.
4. Create a new file app/components/SomeComponent.tsx and observe page refresh. Validate no websocket errors in browser console.
5. Verify LiveReload is still working by editing app/routes/index.tsx and observing the change.

[remix-cla-bot]

Hi @tessellator,

Welcome, and thank you for contributing to Remix!

Before we consider your pull request, we ask that you sign our Contributor License Agreement (CLA). We require this only once.

You may review the CLA and sign it by adding your name to contributors.yml.

Once the CLA is signed, the CLA Signed label will be added to the pull request.

If you have already signed the CLA and received this response in error, or if you have any questions, please contact us at [email protected].

Thanks!

- The Remix team

[remix-cla-bot]

Thank you for signing the Contributor License Agreement. Let's get this merged! 🥳

[tessellator]

This also appears to fix #1601 and #3130

[tessellator]

Closing in favor of #3206