Update duplicate print action message

[MitchLillie]

WHY are these changes introduced?

Fixes https://github.com/Shopify/app-ui/issues/1192

WHAT is this pull request doing?

Updating the error message shown when dev'ing or deploying multiple print extensions with the same target. Also updated to use the handle rather than app name as it is unique.

Before:

After:

How to test your changes?

1. Have an app with multiple print extensions for the same target (wiki)
2. From this repo, run cli-spin pnpm shopify app dev --path ../to-your-app
3. Assert that you see the expected message.

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	71.97% (+0.01% 🔼)	7268/10099
🟡	Branches	69.15% (+0.02% 🔼)	3564/5154
🟡	Functions	71.54%	1941/2713
🟡	Lines	73.26% (+0.01% 🔼)	6844/9342

Test suite run success

1688 tests passing in 785 suites.

Report generated by 🧪jest coverage report action from 379c0e9

[elanalynn]

Perfect.