Add multiple namespaces support to PIT search and finder (#109062)

* initial modifications

* change approach for openPointInTime and add tests for spaces wrapper changes

* fix and add security wrapper tests

* fix export security FTR tests

* update generated doc

* add tests for PIT finder

* NIT

* improve doc

* nits

docs/development/core/server/kibana-plugin-core-server.savedobjectsopenpointintimeoptions.md

@@ -8,13 +8,14 @@
 <b>Signature:</b>
 
 ```typescript
-export interface SavedObjectsOpenPointInTimeOptions extends SavedObjectsBaseOptions 
+export interface SavedObjectsOpenPointInTimeOptions 
 ```
 
 ## Properties
 
 |  Property | Type | Description |
 |  --- | --- | --- |
 |  [keepAlive](./kibana-plugin-core-server.savedobjectsopenpointintimeoptions.keepalive.md) | <code>string</code> | Optionally specify how long ES should keep the PIT alive until the next request. Defaults to <code>5m</code>. |
+|  [namespaces](./kibana-plugin-core-server.savedobjectsopenpointintimeoptions.namespaces.md) | <code>string[]</code> | An optional list of namespaces to be used when opening the PIT.<!-- -->When the spaces plugin is enabled: - this will default to the user's current space (as determined by the URL) - if specified, the user's current space will be ignored - <code>['*']</code> will search across all available spaces |
 |  [preference](./kibana-plugin-core-server.savedobjectsopenpointintimeoptions.preference.md) | <code>string</code> | An optional ES preference value to be used for the query. |
 

docs/development/core/server/kibana-plugin-core-server.savedobjectsopenpointintimeoptions.namespaces.md

@@ -0,0 +1,15 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [kibana-plugin-core-server](./kibana-plugin-core-server.md) &gt; [SavedObjectsOpenPointInTimeOptions](./kibana-plugin-core-server.savedobjectsopenpointintimeoptions.md) &gt; [namespaces](./kibana-plugin-core-server.savedobjectsopenpointintimeoptions.namespaces.md)
+
+## SavedObjectsOpenPointInTimeOptions.namespaces property
+
+An optional list of namespaces to be used when opening the PIT.
+
+When the spaces plugin is enabled: - this will default to the user's current space (as determined by the URL) - if specified, the user's current space will be ignored - `['*']` will search across all available spaces
+
+<b>Signature:</b>
+
+```typescript
+namespaces?: string[];
+```