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/TapeDevicePathSelector.js

@@ -0,0 +1,62 @@
+Ext.define('PBS.form.TapeDevicePathSelector', {
+    extend: 'Proxmox.form.ComboGrid',
+    alias: 'widget.pbsTapeDevicePathSelector',
+
+    allowBlank: false,
+    displayField: 'path',
+    valueField: 'path',
+
+    // type can be 'drives' or 'changers'
+    type: 'drives',
+
+    listConfig: {
+	columns: [
+	    {
+		text: gettext('Path'),
+		dataIndex: 'path',
+		sortable: true,
+		flex: 1,
+		renderer: Ext.String.htmlEncode,
+	    },
+	    {
+		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,
+	    },
+	],
+    },
+
+    initComponent: function() {
+	let me = this;
+	if (me.type !== 'drives' && me.type !== 'changers') {
+	    throw `invalid type '${me.type}'`;
+	}
+
+	let url = `/api2/json/tape/scan-${me.type}`;
+	me.store = {
+	    proxy: {
+		type: 'proxmox',
+		url,
+	    },
+	    autoLoad: true,
+	};
+
+	me.callParent();
+    },
+});