Always populate host theme

[Poitrin]

WHY are these changes introduced?

In order to avoid non-populated host themes, they should be populated every time, until Ruby CLI dependency has been removed.

WHAT is this pull request doing?

Treats a host theme as always createdAtRuntime, so that --generate-tmp-theme is always passed to CLI 2.

How to test your changes?

• shopify app dev in your favorite app directory.

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
• 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	72.83%	4146/5693
🟡	Branches	69.63%	1871/2687
🟡	Functions	70.33%	1095/1557
🟡	Lines	74.12%	3956/5337

Test suite run success

1056 tests passing in 534 suites.

Report generated by 🧪jest coverage report action from 6802b08

[Arkham]

Thank you!