Introduce UniversalFlatEntityFrom (#17367)

# Introduction

Creating a `UniversalFlatEntityFrom` that strips out all the relation
and foreignKey properties in order to replace them with
`UniversalIdentifier` suffix

This data type will be major for the workspace migration workspace
agnostic refactor

## Chore
- renamed `flat-entity.type` to `flat-entity-from.type.ts` ( more
accurate to exported module )
- create static test type over the field metadata entity on quite
complex utils as both coverage and documentation

## Example
Here's an example of a `UniversalFlatEntityFrom<FieldMetadataEntity>`

```ts
const universalFlatFieldMetadata: UniversalFlatFieldMetadata<FieldMetadataType.RELATION> = {
  // Base properties (from FieldMetadataEntity, excluding relations and applicationId)
  universalIdentifier: '550e8400-e29b-41d4-a716-446655440001',
  applicationUniversalIdentifier: '5800681c-088e-4e2b-9fc3-bcf6e8ec2051',
  type: FieldMetadataType.RELATION,
  name: 'firstName',
  label: 'First Name',
  defaultValue: null,
  description: 'The first name of the person',
  icon: 'IconUser',
  standardOverrides: null,
  options: null,
  settings: {
    relationType: RelationType.ONE_TO_MANY,
  },
  isCustom: false,
  isActive: true,
  isSystem: false,
  isUIReadOnly: false,
  isNullable: true,
  isUnique: false,
  isLabelSyncedWithName: true,
  morphId: null,

  // Date properties cast to string
  createdAt: '2024-01-15T10:30:00.000Z',
  updatedAt: '2024-01-15T10:30:00.000Z',

  // ManyToOne relation universal identifiers (from FieldMetadataEntity relations)
  relationTargetFieldMetadataUniversalIdentifier:
    '550e8400-e29b-41d4-a716-446655440012',
  relationTargetObjectMetadataUniversalIdentifier:
    '550e8400-e29b-41d4-a716-446655440013',

  // Join column universal identifiers (foreignKey -> universalIdentifier)
  objectMetadataUniversalIdentifier: '550e8400-e29b-41d4-a716-446655440010',

  // OneToMany relation universal identifiers (array of related entity identifiers)
  viewFieldUniversalIdentifiers: [
    '550e8400-e29b-41d4-a716-446655440020',
    '550e8400-e29b-41d4-a716-446655440021',
  ],
  viewFilterUniversalIdentifiers: ['550e8400-e29b-41d4-a716-446655440030'],
  kanbanAggregateOperationViewUniversalIdentifiers: [],
  calendarViewUniversalIdentifiers: [],
  mainGroupByFieldMetadataViewUniversalIdentifiers: [],
};
```

## Settings
Will hop on the settings typing next. Might not be dynamic but
declarative though

packages/twenty-server/src/engine/core-modules/applicationVariable/types/flat-application-variable.type.ts

@@ -1,4 +1,4 @@
 import { type ApplicationVariableEntity } from 'src/engine/core-modules/applicationVariable/application-variable.entity';
-import { type FlatEntityFrom } from 'src/engine/metadata-modules/flat-entity/types/flat-entity.type';
+import { type FlatEntityFrom } from 'src/engine/metadata-modules/flat-entity/types/flat-entity-from.type';
 
 export type FlatApplicationVariable = FlatEntityFrom<ApplicationVariableEntity>;

packages/twenty-server/src/engine/core-modules/user/types/flat-workspace-member.type.ts

@@ -1,4 +1,4 @@
-import { type FlatEntityFrom } from 'src/engine/metadata-modules/flat-entity/types/flat-entity.type';
+import { type FlatEntityFrom } from 'src/engine/metadata-modules/flat-entity/types/flat-entity-from.type';
 import { type WorkspaceMemberWorkspaceEntity } from 'src/modules/workspace-member/standard-objects/workspace-member.workspace-entity';
 
 export type FlatWorkspaceMember =