fix: make ddev phpmyadmin work again for Gitpod, fixes #15

[stasadev]

The Issue

• ddev phpmyadmin doesn't work in Gitpod #15

How This PR Solves The Issue

Fixes the condition to open the correct port (I chose not to change the forwarded port from 8036 to 8037 in the docker-compose.phpmyadmin-norouter.yaml file because we only "use" HTTP ports in the cloud and it would be confusing if we forwarded the HTTPS port).

Adds a tip about preview mode in Gitpod.

Renames docker-compose.phpmyadmin-norouter.yaml to docker-compose.phpmyadmin_norouter.yaml

Manual Testing Instructions

Test with Gitpod on DDEV HEAD:

ddev get https://github.com/ddev/ddev-phpmyadmin/tarball/20240712_stasadev_launch_gitpod
ddev restart
ddev phpmyadmin

No need to test it with Codespaces because it won't work anyway, I see we don't omit ddev-router in Codespaces, it's in my TODOs.

Automated Testing Overview

Related Issue Link(s)

Release/Deployment Notes

[rfay]

Could we change docker-compose.phpmyadmin-norouter.yaml to docker-compose.phpmyadmin_norouter.yaml while we're here?

Oddly, - sorts before all alpha, and _ sorts after all alpha.

[rfay]

Let's go with this, thanks!