ui: tape: add form fields

this includes selectors for
* Allocation Policy
* Retention Policy
* Drives
* Changers
* Tape Device Paths
* Pools

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

www/tape/form/ChangerSelector.js

@@ -0,0 +1,60 @@
+Ext.define('PBS.form.ChangerSelector', {
+    extend: 'Proxmox.form.ComboGrid',
+    alias: 'widget.pbsChangerSelector',
+
+    allowBlank: false,
+    displayField: 'name',
+    valueField: 'name',
+    value: null,
+    multiSelect: false,
+
+
+    store: {
+	proxy: {
+	    type: 'proxmox',
+	    url: '/api2/json/tape/changer',
+	},
+	autoLoad: true,
+	sorter: 'name',
+    },
+
+    listConfig: {
+	columns: [
+	    {
+		text: gettext('Name'),
+		dataIndex: 'name',
+		sortable: true,
+		flex: 1,
+		renderer: Ext.String.htmlEncode,
+	    },
+	    {
+		text: gettext('Path'),
+		sortable: true,
+		dataIndex: 'path',
+		hidden: true,
+		flex: 1,
+	    },
+	    {
+		text: gettext('Vendor'),
+		dataIndex: 'vendor',
+		sortable: true,
+		flex: 1,
+		renderer: Ext.String.htmlEncode,
+	    },
+	    {
+		text: gettext('Model'),
+		dataIndex: 'model',
+		sortable: true,
+		flex: 1,
+		renderer: Ext.String.htmlEncode,
+	    },
+	    {
+		text: gettext('Serial'),
+		dataIndex: 'serial',
+		sortable: true,
+		flex: 1,
+		renderer: Ext.String.htmlEncode,
+	    },
+	],
+    },
+});