Release Azure.Identity Preview using MSAL for NodeJS Beta

[joshfree]

Currently Azure.Identity for JS does not have feature parity with Azure.Identity for .NET/Java/Python due to the unavailability of a supported version of MSAL for NodeJS.

This work item tracks catching JS up to feature parity using the beta MSAL for NodeJS

• shipping a public preview of Azure.Identity for JS using the first public beta MSAL for NodeJS
• Reviewing and unifying the usage of MSAL / MSAL Cache, per the work done last semester in the other 3 primary languages
• Adding Azure Identity Support for MSAL Configurable Token Refresh
• Adding UserAuthentication API

This work will be kept in a separate feature branch until MSAL for NodeJS reaches a supportable / go-live level of quality, at which point this work can merge back to master and ship GA.

[sophiajt]

dupe of #9778