[MNT-22606] Add properties viewer as form widget (#7278)

* [MNT-22606] Add properties viewer as form widget

* [MNT-22606] Add documentation and fix the params accessor

* [MNT-22606] Fix unit tests

* [MNT-22606] Fix lint

* [MNT-22606] Fix lint

* [MNT-22606] Fix lint

docs/process-services-cloud/widgets/properties-viewer.widget.md

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+---
+Title: APA Properties Viewer Widget
+Added: v4.7.0
+Status: Active
+---
+
+# [APA Properties Viewer Widget](../../../lib/process-services-cloud/src/lib/form/components/widgets/properties-viewer/properties-viewer.widget.ts "Defined in properties-viewer.widget.ts")
+
+It makes use of the [content metadata card](../../content-services/components/content-metadata-card.component.md "content-metadata-card") to display the properties of the selected file in an attach widget in a form.
+
+## Basic Usage
+
+This a form widget so it receives the [`FormFieldModel`](../../core/models/form-field.model.md) form the form renderer with the following meanings:
+
+| Accessor | Type | Description |
+| -------- | ---- | ----------- |
+|`field.value`| `string` | The nodeId of the node which properties are going to be displayed |
+|`field.params.propertiesViewerOptions` | `object` | An object containing all the [properties of the content metadata card](../../content-services/components/content-metadata-card.component.md#properties "content-metadata-card properties") |
+
+## Class members
+
+### Properties
+
+| Name | Type | Default value | Description |
+| ---- | ---- | ------------- | ----------- |
+| field | `FormFieldModel` |  | The field information |
+
+### Events
+
+| Name | Type | Description |
+| ---- | ---- | ----------- |
+| nodeContentLoaded | [`EventEmitter`](https://angular.io/api/core/EventEmitter)`<Node>` | Emitted when the properties to be displayed are retrieved from the content service. |
+| fieldChanged | [`EventEmitter`](https://angular.io/api/core/EventEmitter)`<string>` | Emitted when the field changes |