chore: Update devtools scripts to avoid opening browser window

[camdecoster]

Description

Print a URL to open the dev server when running npm start or npm run regl-codegen instead of opening a browser window directly.

Closes #7776.

Changes

• Update devtools server scripts
• Fix issue with loading plotly.js in regl codegen
• Fix issue with esbuild config for regl codegen
• Remove unused dependency
• Update docs per above changes

Testing

• Run npm start or npm run regl-codegen
• Note that no browser window opens
• Note that the server URL is printed in the terminal

Notes

• regl codegen has been broken for a while
• In a future PR, this will run in CI if the proper files have been changed

[alexcjohnson]

Looks great!