If an import statement to a missing module occurs when parsing in a
project with no dependencies the error message has the following form:
```
The module Foo does not exist.
It should be in /Users/paul/heliax/juvix-2023/tests/negative/NoDependencies/Foo.juvix
or in one of the dependencies:
```
This PR changes this error message to the `or in one of the
dependencies:` line is omitted from the error message when there are no
dependencies in the project.
This commit also adds a negative parse error test for missing module.
