Allow cloning of ReadWriteLogRecord (#4090)

Follows
#4062

## Why

1. There is a need to make a deep copy of a `ReadWriteRecord` in order
to implement an experimental isolating processor outside of the SDK (as
it is experimental, we prefer to land it to contrib repository first).
2. Allow fine-grained control for the users to make a deep copy only
when necessary. This allows users to have more control on the processing
e.g. pass a clone to asynchronous processor to avoid race conditions or
make performance improvements.

CHANGELOG.md

@@ -28,6 +28,9 @@ release.
 
 ### Logs
 
+- The SDK MAY provide an operation that makes a deep clone of a `ReadWriteLogRecord`.
+  ([#4090](https://github.com/open-telemetry/opentelemetry-specification/pull/4090))
+
 ### Events
 
 ### Resource

specification/logs/sdk.md

@@ -235,6 +235,12 @@ the following information added to the [LogRecord](data-model.md#log-and-event-r
 * [`SpanId`](./data-model.md#field-spanid)
 * [`TraceFlags`](./data-model.md#field-traceflags)
 
+The SDK MAY provide an operation that makes a deep clone of a `ReadWriteLogRecord`.
+The operation can be used to implement the [isolating processor](#isolating-processor)
+or by asynchronous processors (e.g. [Batching processor](#batching-processor))
+to avoid race conditions on the log record that is not required to be
+concurrent safe.
+
 ## LogRecord Limits
 
 `LogRecord` attributes MUST adhere to