Add isolating log record processor

[pellared]

Per open-telemetry/opentelemetry-specification#4062

Isolating processor

Status: Development

This is an implementation of LogRecordProcessor ensuring the log record
passed to OnEmit of the configured processor does not share mutable data
with subsequent registered processors.
For example, the OnEmit implementation of the isolating processor can be
a decorator that makes a deep copy of the log record before passing it to
the configured processor.

Configurable parameters:

• processor - processor to be isolated.