Connect - Relation on FE Importer (#13213)

Done : 
- Relation connect on FE Importer
- Remove templating on SpreadsheetMatchedColumn type
- Remove useless files on import
- Remove AvailableFieldsForImport type + Update SpreadsheetImportField
type and SpreadsheetImportFieldOption


To test : 
- Try import opportunities on Apple wk 
[using this
file](https://github.com/user-attachments/files/21233720/Test.import.-.opportunities-sample.csv)


closes : https://github.com/twentyhq/core-team-issues/issues/1090

packages/twenty-front/src/modules/spreadsheet-import/utils/uniqueEntries.ts

@@ -3,10 +3,10 @@ import uniqBy from 'lodash.uniqby';
 import { MatchColumnsStepProps } from '@/spreadsheet-import/steps/components/MatchColumnsStep/MatchColumnsStep';
 import { SpreadsheetMatchedOptions } from '@/spreadsheet-import/types/SpreadsheetMatchedOptions';
 
-export const uniqueEntries = <T extends string>(
+export const uniqueEntries = (
   data: MatchColumnsStepProps['data'],
   index: number,
-): Partial<SpreadsheetMatchedOptions<T>>[] =>
+): Partial<SpreadsheetMatchedOptions>[] =>
   uniqBy(
     data.map((row) => ({ entry: row[index] })),
     'entry',