message: convert all the regex operators from /pattern/ to {"$regex":"pattern"} as mentioned in the issue\PR comment
diff: @@ -317,17 +317,17 @@ const formatQuery = (
  if (['<', '<=', '=', '!=', '>', '>='].includes(rule.operator)) {
  return `{"${rule.field}":{"${mongoOperator}":${value}}}`;
  } else if (rule.operator === 'contains') {
  - return `{"${rule.field}":"/${rule.value}/"}`;
  + return `{"${rule.field}":"${rule.value}"}`;
  } else if (rule.operator === 'beginsWith') {
  - return `{"${rule.field}":"/^${rule.value}/"}`;
  + return `{"${rule.field}":"^${rule.value}"}`;
  } else if (rule.operator === 'endsWith') {
  - return `{"${rule.field}":"/${rule.value}$/"}`;
  + return `{"${rule.field}":"${rule.value}$"}`;
  } else if (rule.operator === 'doesNotContain') {
  - return `{"${rule.field}":{"$not":"/${rule.value}/"}}`;
  + return `{"${rule.field}":{"$not":"${rule.value}"}}`;
  } else if (rule.operator === 'doesNotBeginWith') {
  - return `{"${rule.field}":{"$not":"/^${rule.value}/"}}`;
  + return `{"${rule.field}":{"$not":"^${rule.value}"}}`;
  } else if (rule.operator === 'doesNotEndWith') {
  - return `{"${rule.field}":{"$not":"/${rule.value}$/"}}`;
  + return `{"${rule.field}":{"$not":"${rule.value}$"}}`;
  } else if (rule.operator === 'null') {
  return `{"${rule.field}":null}`;
  } else if (rule.operator === 'notNull') {
  