Allow CORS for checking if GraphiQL is running

[thomfoolery]

WHY are these changes introduced?

Shopify.dev wants to verify CLI's GraphiQL server is running so we can forward code examples from our LLM assistant.

CORS policies currently restrict us from pinging the GraphiQL server.

WHAT is this pull request doing?

This PR loosens the CORS policy for /graphiql/ping

How to test your changes?

1. Run shopify app dev inside a Shopify app (with this code checked out)
2. Open shopify.dev in a web browser
3. Open the developer tools console and run fetch('http://localhost:3457/graphiql/ping').then(console.log)
4. See a response object come back with ok === true

Post-release steps

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've made sure that any changes to dev or deploy have been reflected in the internal flowchart.

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	71.89% (-0.03% 🔻)	7236/10065
🟡	Branches	69.06%	3565/5162
🟡	Functions	71.54% (-0.03% 🔻)	1936/2706
🟡	Lines	73.16% (-0.03% 🔻)	6813/9313

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🔴	... / server.ts	1.3% (-0.07% 🔻)	0%	0%	1.37% (-0.08% 🔻)

Test suite run success

1684 tests passing in 781 suites.

Report generated by 🧪jest coverage report action from 5f10367