Added diagnostic logging

[jeremydvoss]

Added diagnostic and status loggers. These loggers are only active in App Service environments. The status logger outputs during initialization and rewrites the file each time. It is used only to get the current status of the distro's initialization and check if something went wrong. The diagnostic logger handler's function is twofold.

1. It's added to the "opentelemetry" logger so as to capture all opentelemetry logs and send them to a file for App Service to pick up.
2. The AzureDiagnosticLogger class has methods through which distro-level logs can be created.

Node Loggers: https://dev.azure.com/msazure/One/_git/MGMT-AppInsights-NodeJS-IPA?path=/src/Loader.ts

[lzchen]

@jeremydvoss

Might I suggest splitting up this PR into diagnostic logger and status logger? Seems like that would be easier to review and merge in.

[jeremydvoss]

As Leighton suggested, I removed status logger from this pr.