[CHORE] Avoid isDefined duplicated reference, move it to twenty-shared (#9967)

# Introduction
Avoid having multiple `isDefined` definition across our pacakges
Also avoid importing `isDefined` from `twenty-ui` which exposes a huge
barrel for a such little util function

## In a nutshell
Removed own `isDefined.ts` definition from `twenty-ui` `twenty-front`
and `twenty-server` to move it to `twenty-shared`.
Updated imports for each packages, and added explicit dependencies to
`twenty-shared` if not already in place

Related PR https://github.com/twentyhq/twenty/pull/9941

packages/twenty-front/src/modules/workflow/workflow-variables/hooks/useAvailableVariablesInWorkflowStep.ts

@@ -13,7 +13,7 @@ import { filterOutputSchema } from '@/workflow/workflow-variables/utils/filterOu
 import { getTriggerStepName } from '@/workflow/workflow-variables/utils/getTriggerStepName';
 import isEmpty from 'lodash.isempty';
 import { useRecoilValue } from 'recoil';
-import { isDefined } from 'twenty-ui';
+import { isDefined } from 'twenty-shared';
 import { isEmptyObject } from '~/utils/isEmptyObject';
 
 export const useAvailableVariablesInWorkflowStep = ({