[Documentation] Deprecate databricks_sql_visualization and databricks_sql_widget resource. (#4924)

## Changes
<!-- Summary of your changes that are easy to understand -->
These resources are deprecated.

## Tests
<!--
How is this tested? Please see the checklist below and also describe any
other relevant tests
-->
Existing tests

Author: tanmay-db

NEXT_CHANGELOG.md

@@ -13,6 +13,7 @@
 ### Documentation
 
 * Document `email_notifications` block in model serving resources ([#4910](https://github.com/databricks/terraform-provider-databricks/pull/4910))
+* Deprecate `databricks_sql_visualization` and `databricks_sql_widget` resource. ([#4924](https://github.com/databricks/terraform-provider-databricks/pull/4924))
 
 ### Exporter
 

docs/resources/sql_visualization.md

@@ -3,6 +3,10 @@ subcategory: "Databricks SQL"
 ---
 # databricks_sql_visualization Resource
 
+!> This resource is deprecated and will be removed in future.
+
+-> Please switch to [databricks_dashboard](dashboard.md) to author new AI/BI dashboards using the latest tooling
+
 To manage [SQLA resources](https://docs.databricks.com/sql/get-started/concepts.html) you must have `databricks_sql_access` on your [databricks_group](group.md#databricks_sql_access) or [databricks_user](user.md#databricks_sql_access).
 
 -> documentation for this resource is a work in progress.
@@ -61,7 +65,7 @@ If you have lots of visualizations to declare, it might be cleaner to separate t
     ```
 
 - resource definitions
-  
+
     ```hcl
     ##q1vx.tf
 

docs/resources/sql_widget.md

@@ -3,6 +3,8 @@ subcategory: "Databricks SQL"
 ---
 # databricks_sql_widget Resource
 
+!> This resource is deprecated and will be removed in future.
+
 -> Please switch to [databricks_dashboard](dashboard.md) to author new AI/BI dashboards using the latest tooling
 
 To manage [SQL resources](https://docs.databricks.com/sql/get-started/concepts.html) you must have `databricks_sql_access` on your [databricks_group](group.md#databricks_sql_access) or [databricks_user](user.md#databricks_sql_access).

sql/resource_sql_visualization.go

@@ -160,6 +160,7 @@ func ResourceSqlVisualization() common.Resource {
 		})
 
 	return common.Resource{
+		DeprecationMessage: "This resource is deprecated and will be removed in future. Please switch to databricks_dashboard to author new AI/BI dashboards using the latest tooling.",
 		Create: func(ctx context.Context, data *schema.ResourceData, c *common.DatabricksClient) error {
 			var v VisualizationEntity
 			av, err := v.toAPIObject(s, data)

sql/resource_sql_widget.go

@@ -272,6 +272,7 @@ func ResourceSqlWidget() common.Resource {
 		})
 
 	return common.Resource{
+		DeprecationMessage: "This resource is deprecated and will be removed in future. Please switch to databricks_dashboard to author new AI/BI dashboards using the latest tooling.",
 		Create: func(ctx context.Context, data *schema.ResourceData, c *common.DatabricksClient) error {
 			var w WidgetEntity
 			aw, err := w.toAPIObject(s, data)