Generating a project with an artifact id starting with a number breaks the build

When you generate a project from the archetype, starting off with a number char, the build breaks.

```
filePath=jcr_root/conf/202180sandbox/settings/wcm/policies/.content.xml, nodePath=/conf/202180sandbox/settings/wcm/policies
11:36:46,775 [main] [INFO] ValidationViolation: "jackrabbit-filter: Ancestor node '/content/dam/202180sandbox' is not covered by any of the filter rules. Preferably depend on a package that provides this node or include it in the filter rules!", filePath=jcr_root/content/dam/202180sandbox/.content.xml
```

The reason is we use XML here like:


We could prefix this XML with something like project- to prevent this, or we can provide some sort of constraint on the input or in the groovy script to check the artifactId starts with characters.

Start by generating a project with an artifactId beginning with a number and inspect the XML under jcr_root/conf/202180sandbox and jcr_root/content/dam/202180sandbox, along with the Groovy script mentioned in the issue. Confirm the generated build no longer reports the jackrabbit-filter validation violation for the numeric artifactId.

Written by the indexing model from the issue text.