fix(Table): expandFixed prop type definition (#5539)，close #5535

Author: buqiyuan

components/table/Table.tsx

@@ -126,7 +126,10 @@ export const tableProps = () => {
       default: undefined,
     },
     direction: { type: String as PropType<TableProps['direction']>, default: undefined },
-    expandFixed: { type: Boolean as PropType<TableProps['expandFixed']>, default: undefined },
+    expandFixed: {
+      type: [Boolean, String] as PropType<TableProps['expandFixed']>,
+      default: undefined,
+    },
     expandColumnWidth: {
       type: Number as PropType<TableProps['expandColumnWidth']>,
       default: undefined,

components/vc-table/Table.tsx

@@ -98,7 +98,7 @@ export interface TableProps<RecordType = DefaultRecordType> {
   direction?: 'ltr' | 'rtl';
 
   // Expandable
-  expandFixed?: boolean;
+  expandFixed?: 'left' | 'right' | boolean;
   expandColumnWidth?: number;
   expandedRowKeys?: Key[];
   defaultExpandedRowKeys?: Key[];