Standard index as code introduction + type refactor (#16426)

# Introduction
Related https://github.com/twentyhq/core-team-issues/issues/1995

In this PR we're introducing the standard index tools for their
declaration
Also adding a common typing in order to have a simily consistency across
standard builders

Will implement remaining standard index builder in an other PR

packages/twenty-server/src/engine/metadata-modules/index-metadata/utils/generate-flat-index.util.ts

@@ -10,7 +10,7 @@ import { type FlatIndexMetadata } from 'src/engine/metadata-modules/flat-index-m
 import { type FlatObjectMetadata } from 'src/engine/metadata-modules/flat-object-metadata/types/flat-object-metadata.type';
 import { generateDeterministicIndexNameV2 } from 'src/engine/metadata-modules/index-metadata/utils/generate-deterministic-index-name-v2';
 
-type GenerateFlatIndexArgs = {
+export type GenerateFlatIndexArgs = {
   flatObjectMetadata: FlatObjectMetadata;
   objectFlatFieldMetadatas: FlatFieldMetadata[];
   flatIndex: Omit<FlatIndexMetadata, 'name'>;