Streamlined eslint usage for eslint9 w/ cds8 (#719)

* Streamlined eslint usage

* import from @sap/cds instead of @sap/cds/lib

* Using @sap/cds/eslint.js

* eslint.config.mjs aktualisieren

* Adjusted eslint usage for eslint9 with cds8

data-viewer/srv/data-service.js

@@ -18,7 +18,7 @@ class DataService extends cds.ApplicationService { init(){
       .sort((e1, e2) => e1.name.localeCompare(e2.name))
       .map(e => {
         const columns = Object.entries(e.elements)
-          .filter(([_, el]) => !(el instanceof cds.Association)) // exclude assocs+compositions
+          .filter(([,el]) => !(el instanceof cds.Association)) // exclude assocs+compositions
           .map(([name, el]) => { return { name, type: el.type, isKey:!!el.key }})
         return { name: e.name, columns }
       })