Improve error reporting for build telemetry reporter

[bernardnormier]

Currently, when the build telemetry reporter code throws an exception, the program fails with exit code 1 and .NET prints a stack trace for the exception. The MSBuild task "continues on error" so it doesn't affect the build (it just shows this task failing with exit code 1).

We should improve this error handling as follows:

• for expected errors, catch the exception/error, print/log a short message and return 0
  For example, when the build telemetry server is unreachable, or the reporting timed out
• for unexpected errors, catch the exception/error, print/log the exception message + inner exception name/message (if any), but not the full stack trace, and return 1