Allows user to specify style id for Tables

Allows user to specify the style Id which will be added in the form of:
<w:tblStyle w:val="TableGrid"/>

As specified in table Structure in http://officeopenxml.com/WPtable.php

src/file/table/table-properties/table-properties.ts

@@ -6,6 +6,7 @@ import { TableBorders } from "./table-borders";
 import { TableCellMargin } from "./table-cell-margin";
 import { ITableFloatOptions, TableFloatProperties } from "./table-float-properties";
 import { TableLayout, TableLayoutType } from "./table-layout";
+import { TableStyle } from "./table-style";
 import { PreferredTableWidth } from "./table-width";
 
 export class TableProperties extends IgnoreIfEmptyXmlComponent {
@@ -46,4 +47,9 @@ export class TableProperties extends IgnoreIfEmptyXmlComponent {
 
         return this;
     }
+
+    public setStyle(styleId: string): TableProperties {
+        this.root.push(new TableStyle(styleId));
+        return this;
+    }
 }

src/file/table/table-properties/table-style.ts

@@ -0,0 +1,15 @@
+import { Attributes, XmlComponent } from "file/xml-components";
+
+export class TableStyle extends XmlComponent {
+    public readonly styleId: string;
+
+    constructor(styleId: string) {
+        super("w:tblStyle");
+        this.styleId = styleId;
+        this.root.push(
+            new Attributes({
+                val: styleId,
+            }),
+        );
+    }
+}