1. Add CustomRadix{Def,Apply}Annotation to define and apply custom radix.
2. Add CustomRadixConfigFileAnnotation to output a JSON config file so
   users can generate scripts on their own.

Reviewed-by: Jiuyang Liu <liu@jiuyang.me>

Improve ANTLR Parser

The ANTLR-generated concrete syntax tree (CST) takes up much more memory
than the parsed .fir file. By using a Listener, we can construct the
FIRRTL AST live with CST construction and null out the CST as we consume
pieces of it. Not only does this improve performance, it drastically
reduces max memory use for the parser.

Tweak the grammar to handle references without left-recursion. Also
split references and subreferences out from the regular expression rule
to make their parsing more efficient.

The classes should not really be part of the firrtl public API to begin
with and they cause issues during ScalaDoc generation.

Co-authored-by: Jack Koenig <koenig@sifive.com>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Also remove all related APIs:

ComposableOptions
HasParser
CommonOptions
HasCommonOptions
FirrtlExecutionOptions
HasFirrtlOptions
FirrtlExecutionResult
FirrtlExecutionSuccess
FirrtlExecutionFailure
ExecutionOptionsManager
firrtl.stage.DriverCompatibility.firrtlResultView
logger.Logger.makeScope
OutputConfig
SingleFile
OneFilePerModule

* Change default LogLevel to None which means "unset"

Logger.getGlobalLevel then returns LogLevel.Warn when the current value
is LogLevel.None. This preserves the behavior of the default being
"Warn" but now uses LogLevel.None to indicate "I'm not setting the
value." This resolves issues where it was not possible to tell if
annotations were actually setting the log level or if the default level
of warn was just being filled in.

Co-authored-by: sinofp <sinofp@tuta.io>
Co-authored-by: Jack Koenig <koenig@sifive.com>

Co-authored-by: sinofp <sinofp@tuta.io>

Co-authored-by: sinofp <sinofp@tuta.io>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

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Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

* remove firrtl.Utils.get_flip.

* remove firrtl.Utils.indent.

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Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

* Update scala-parallel-collections to 1.0.4

* Update scala-parallel-collections to 1.0.4

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

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Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

* Update sbt-scalafix to 0.9.32

* Update scala-library, scala-reflect to 2.13.7

* Add option to disable random mem/reg init

Co-authored-by: Jiuyang Liu <liu@jiuyang.me>

* fix for code review.

Co-authored-by: SharzyL <me@sharzy.in>

An application like barstools may contain a main that loads an annotations file containing
annotation classes that are not on it's classpath. This change allows unknown annotations
to be preserved by wrapping them in a UnrecognizedAnnotation. If annotations are then output
to a file, they will be unwrapped during serialization
This feature can be enabled via an AllowUnrecognizedAnnotations annotation

Co-authored-by: chick <chick.markley@sifive.com>
Co-authored-by: Jack Koenig <koenig@sifive.com>

Add defname, parameter to extmodule spec, NFC

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

We never tested the case where the width of the
numerator was less than the denominator.
This should fix any issue with this combination.