All required properties should have `"minLength": 1`

If a property is required, it should also not be an empty string. There are many places in the BOM schema where we use `"required": [...]` but do not also verify that these properties have `"minLength": 1`.

An example is `.components[].name`: https://github.com/CycloneDX/specification/blob/8e131b1688ccfe41e1bfdd4b3280f33dcc06d04c/schema/bom-1.6.schema.json#L831

It may be that optional properties should have this constraint as well. Consider the following example:

```json
{
"type": "library",
"name": "whatever",
"version": ""
}
```

If `whatever` does not have a version, it would be more clear if that key were to be omitted rather than provided as an empty string.