Core: Correctly resolve injectEnvironmentFiles default value

[clemyan]

What's the problem this PR addresses?

In Configuration.find, the default value of injectEnvironmentFiles ([".env.yarn?"]) is resolved before projectCwd, causing it to anchor to startingCwd instead.

Fixes #6111

How did you fix it?

Move resolving projectCwd to before resolving default values of any config

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.