WIP: tests on checkbox component

...nents/criteria/search-type/between-date.component.spec.ts

...components/criteria/search-type/between-date.component.ts

...components/criteria/search-type/between.component.spec.ts

...arch/components/criteria/search-type/between.component.ts

...omponents/criteria/search-type/checkbox.component.spec.ts

...rch/components/criteria/search-type/checkbox.component.ts

...omponents/criteria/search-type/datalist.component.spec.ts

...rch/components/criteria/search-type/datalist.component.ts

...ch/components/criteria/search-type/date.component.spec.ts

.../search/components/criteria/search-type/date.component.ts

...omponents/criteria/search-type/datetime.component.spec.ts

...ts/criteria/search-type/select-multiple.component.spec.ts