fix(sedml): make variable ids unique for data generators

Otherwise biosimulations errors;

```
Multiple objects have the following ids:\n      -
hhpop_0_bioPhys1_membraneProperties_KConductances_KConductance_n_q\n
- hhpop_0_bioPhys1_membraneProperties_NaConductances_NaConductance_h_q\n
  -
  hhpop_0_bioPhys1_membraneProperties_NaConductances_NaConductance_m_q\n
  - hhpop_0_v\n      - time""
```

src/main/java/org/lemsml/export/sedml/SEDMLWriter.java

@@ -170,7 +170,7 @@ else if(modelFormat == Format.CELLML)
                         }
 
                         String genId = prefix + id + "_" + lineOrColumnComp.getID().replace(" ","_");
-                        String varFull = pop + "_" + num+segid + "_" + var;
+                        String varFull = genId + "_" +  pop + "_" + num+segid + "_" + var;
 
                         startElement(main, "dataGenerator", "id=" + genId, "name=" + genId);
                         startElement(main, "listOfVariables");