Restart web app via native ARM restart instead of chaining Stop → Start

[Copilot]

restartWebApp implemented Restart by chaining appService.Stop then appService.Start. This left the app Stopped whenever Start failed (transient ARM 5xx, throttling, network), and incurred a full deallocate/reallocate cold-start window rather than a worker recycle.

Changes

• src/commands/restartWebApp.ts: replaced the Stop → Start command chaining with a direct native restart against WebSiteManagementClient, wrapped in the same runWithTemporaryDescription + output-channel logging pattern as startWebApp.ts / stopWebApp.ts.
• Slot handling: dispatches to webApps.restartSlot when slotName is present, otherwise webApps.restart.

Note: the issue's suggested client.restart() on the SiteClient wrapper doesn't exist — that wrapper only exposes stop() / start() — so this uses the raw ARM client via createWebSiteClient, matching existing usage elsewhere in the extension.

const client = await createWebSiteClient([context, node.subscription]);
await node.runWithTemporaryDescription(context, localize('restarting', "Restarting..."), async () => {
    ext.outputChannel.appendLog(restartingApp);
    if (site.slotName) {
        await client.webApps.restartSlot(site.resourceGroup, site.siteName, site.slotName);
    } else {
        await client.webApps.restart(site.resourceGroup, site.siteName);
    }
    ext.outputChannel.appendLog(restartedApp);
});