Enable MsalClient to opt-in to performance telemetry

[amcclain]

I would like to have our MSAL client class import the BrowserPerformanceClient class and support a config-driven flag to enable it.

See https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-browser/docs/performance.md

Note too option to have performance tracing stopped, which might be something we wish to have happen automatically, eg after full app init (as a further config option around this feature).