Deprecate MessageHandler. Rework all tools to use Python's logging

[amykyta3]

Background

One long-standing issue about the compiler I have been meaning to address is the mechanism for reporting error & warning messages.
Rather than using Python's built-in logging library, I had for some reason implemented a custom message handling mechanism that is tightly bound to the mechanics of the compiler.

This is problematic for several reasons:

• Poor control of message handling, filtering, and output
• Difficult to use with compiler-adjacent tools like PeakRDL - one has to pass around a reference to the message handler class
• Reinvents something that already exists - Python's logging facility

Changes

Migrate the systemrdl-compiler to emit messages using Python's logging facility.

Specifically, the following changes will be made:

• Provide a new logging Formatter class that is specifically tailored for handling log messages that contain contextual RDL source referencing information. (basically provide a formatter that generates the exact same pretty error messages as before). To keep things easy to use, this formatter, along with a StreamHandler will be auto-loaded if no other handlers are found in the design.
• Implement an equivalent mechanism for trapping and escalating errors during compilation & elaboration (escalate to RDLCompileError exception where appropriate)
• Remove systemrdl.messages.MessagePrinter and systemrdl.messages.MessageHandler
• Remove the optional message_printer argument to the RDLCompiler constructor
• Remove references and usage of the MessageHandler at various points of the API (RDLCompiler.msg, RDLImporter.msg, and other commonly-used places)

Migration plan & compatibility

In nearly all cases, this will not affect anyone since I have not seen much reliance on overriding the default message printer, or other API usages. That said, since this represents a change to a small portion of the publicly-facing API, a proper deprecation cycle will be used in case these changes affect other users.
UPDATE: punting this to the v2.0 update of the compiler instead of hacking together a sloppy compatibility bridge.

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