Display field for app management errors

[amcaplan]

WHY are these changes introduced?

Fixes https://github.com/Shopify/develop-app-inner-loop/issues/2487

We are not properly displaying app management errors - the field is not included in the error message.

Turns out this is due to discrepancies in the error format coming from Partners vs. App Management.

WHAT is this pull request doing?

Updates the error handling so we always display the field if available.

Note much of this PR is handling that appVersion is nullable (and will be null when the version fails to be created), which we weren't allowing for previously.

How to test your changes?

1. In a dev environment, make this change
2. Add this content to your app TOML:

   [[webhooks.subscriptions]]
   compliance_topics = ["customers/data_request", "customers/redact", "shop/redact"]
   uri = "https://example.com"

3. Try to deploy your app

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

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[github-actions]

We detected some changes at packages/*/src and there are no updates in the .changeset.
If the changes are user-facing, run "pnpm changeset add" to track your changes and include them in the next release CHANGELOG.

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	75.61% (+0.01% 🔼)	9055/11976
🟡	Branches	70.87% (+0.02% 🔼)	4420/6237
🟡	Functions	75.4% (+0.01% 🔼)	2376/3151
🟡	Lines	76.12% (+0.02% 🔼)	8551/11233

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / deploy.ts	87.5% (+0.32% 🔼)	83.33% (-4.17% 🔻)	87.5%	89.47% (+0.28% 🔼)
🟢	... / app-event-watcher.ts	95.18% (-1.2% 🔻)	86.49% (-2.7% 🔻)	95.45%	100%

Test suite run success

2044 tests passing in 913 suites.

Report generated by 🧪jest coverage report action from b1e24df