fix: default appPath in new project

[janoshrubos]

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What is the current behavior?

After creating a new project based on a template, we write the default config. In some cases, the appPath is different for a template.

What is the new behavior?

Default config writes appPath based on what folder exists in the template project.
Possible appPaths: app, src.

Fixes #5465

[rigor789]

LGTM