Add terminate ingest processor (#3003)

(cherry picked from commit bcfdc95)

Author: PeteGillinElastic

specification/_doc_ids/table.csv

@@ -596,6 +596,7 @@ stop-transform,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/
 supported-flags,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/query-dsl-simple-query-string-query.html#supported-flags
 tasks,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/tasks.html
 templating-role-query,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/field-and-document-access-control.html#templating-role-query
+terminate-processor,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/terminate-processor.html
 time-value,https://github.com/elastic/elasticsearch/blob/{branch}/libs/core/src/main/java/org/elasticsearch/core/TimeValue.java
 trim-processor,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/trim-processor.html
 unfreeze-index-api,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/unfreeze-index-api.html

specification/ingest/_types/Processors.ts

@@ -230,6 +230,12 @@ export class ProcessorContainer {
    * @doc_id split-processor
    */
   split?: SplitProcessor
+  /**
+   * Terminates the current ingest pipeline, causing no further processors to be run.
+   * This will normally be executed conditionally, using the `if` option.
+   * @doc_id terminate-processor
+   */
+  terminate?: TerminateProcessor
   /**
    * Trims whitespace from a field.
    * If the field is an array of strings, all members of the array will be trimmed.
@@ -1279,6 +1285,8 @@ export class SplitProcessor extends ProcessorBase {
   target_field?: Field
 }
 
+export class TerminateProcessor extends ProcessorBase {}
+
 export class TrimProcessor extends ProcessorBase {
   /**
    * The string-valued field to trim whitespace from.