Extract verbosity as a separate field in the IR stream

[diy1]

Request

Currently verbosity is not tracked as a dedicated field in the IR stream (only as part of the log message). This creates a few issues when viewing the log with the log viewer:

• Some verbosity cannot be correctly recognized. For example, the log viewer currently only recognize verbosities from Java loggers, so it may not correctly recognize certain Python logger's verbosity (e.g., WARNING and CRITICAL).
• The log viewer needs to parse out the verbosity from the log message when the file is loaded. This is unnecessary given that verbosity is already tracked in the logging library.

Possible implementation

Track verbosity field in the IR stream format.