Add split event processor for dataprepper (opensearch-project#6682)

* Add split event processor for dataprepper

Signed-off-by: srigovs <[email protected]>

* Adding usage example

* Update split-event.md

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Signed-off-by: Naarcha-AWS <[email protected]>

* Apply suggestions from code review

Co-authored-by: Nathan Bower <[email protected]>
Signed-off-by: Naarcha-AWS <[email protected]>

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Signed-off-by: srigovs <[email protected]>
Signed-off-by: Naarcha-AWS <[email protected]>
Co-authored-by: Naarcha-AWS <[email protected]>
Co-authored-by: Nathan Bower <[email protected]>

_data-prepper/pipelines/configuration/processors/split-event.md

@@ -0,0 +1,52 @@
+---
+layout: default
+title: split-event
+parent: Processors
+grand_parent: Pipelines
+nav_order: 56
+---
+
+# split-event
+
+The `split-event` processor is used to split events based on a delimiter and generates multiple events from a user-specified field.
+
+## Configuration
+
+The following table describes the configuration options for the `split-event` processor.
+
+| Option           | Type    | Description                                                                                   |
+|------------------|---------|-----------------------------------------------------------------------------------------------|
+| `field`          | String  | The event field to be split.                                                           |
+| `delimiter_regex`| String  | The regular expression used as the delimiter for splitting the field.                         |
+| `delimiter`      | String  | The delimiter used for splitting the field. If not specified, the default delimiter is used.  |
+
+# Usage
+
+To use the `split-event` processor, add the following to your `pipelines.yaml` file:
+
+```
+split-event-pipeline:
+  source:
+    http:
+  processor:
+    - split_event:
+        field: query
+        delimiter: ' '    
+  sink:
+    - stdout:
+```
+{% include copy.html %}
+
+When an event contains the following example input:
+
+```
+{"query" : "open source", "some_other_field" : "abc" }
+```
+
+The input will be split into multiple events based on the `query` field, with the delimiter set as white space, as shown in the following example:
+
+```
+{"query" : "open", "some_other_field" : "abc" }
+{"query" : "source", "some_other_field" : "abc" }
+```
+