refactor: standardize JsonStringified casing (#20101)

## Summary
- Rename safeParseRelativeDateFilterJSONStringified to
safeParseRelativeDateFilterJsonStringified
- Update the matching utility file, exports, tests, and workflow usages

Part of #19839.

## Validation
- CI passed

packages/twenty-front/src/modules/workflow/workflow-steps/filters/components/WorkflowStepFilterValueInput.tsx

@@ -27,7 +27,7 @@ import {
 import {
   isDefined,
   parseJson,
-  safeParseRelativeDateFilterJSONStringified,
+  safeParseRelativeDateFilterJsonStringified,
   type RelativeDateFilter,
 } from 'twenty-shared/utils';
 import { parseBooleanFromStringValue } from 'twenty-shared/workflow';
@@ -151,7 +151,7 @@ export const WorkflowStepFilterValueInput = ({
   const isRelativeDateFilter =
     isDateField && stepFilter.operand === ViewFilterOperand.IS_RELATIVE;
 
-  const relativeDateFilter = safeParseRelativeDateFilterJSONStringified(
+  const relativeDateFilter = safeParseRelativeDateFilterJsonStringified(
     stepFilter.value,
   );