[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-server/src/utils/compute-display-name.ts

@@ -1,5 +1,6 @@
+import { isDefined } from 'twenty-shared';
+
 import { FullNameMetadata } from 'src/engine/metadata-modules/field-metadata/composite-types/full-name.composite-type';
-import { isDefined } from 'src/utils/is-defined';
 
 export const computeDisplayName = (
   name: FullNameMetadata | null | undefined,

packages/twenty-server/src/utils/is-defined.ts

@@ -1,3 +0,0 @@
-export const isDefined = <T>(value: T | null | undefined): value is T => {
-  return value !== null && value !== undefined;
-};