This adds support for kafka serdes-protobuf deserialization via KafkaTools#protobufSpec.

There is an extensive amount of unit testing, both in the form of "how does this message structure gets parsed into
column types" and "how do schema changes get adapted into the same table".

While this feature is primarily targetted for use via KafkaTools, the underlying extensions-protobuf library is
generalized to work in other cases as well. For example, it would work just as well at parsing protobuf messages via
gRPC or websockets (at which point, it could easily be adapted into a blink table).

The implementation is underpinned by a set a functional interfaces for extracting primitives or Objects from a
generic type; in the case of protobuf, the generic type is com.google.protobuf.Message. Coupled with functional
composition, these interfaces provide useful primitives for fluently expressing and executing parsing expressions in
a reusable way.

See https://docs.confluent.io/platform/current/schema-registry/fundamentals/serdes-develop/serdes-protobuf.html

Fixes deephaven#3832

…future.