Add missing tool types and schema enhancements to google_ces_tool resource

[modular-magician]

Add missing tool types and schema enhancements to google_ces_tool

This PR completes the schema coverage for the google_ces_tool resource in Magic Modules to bring it into full parity with the Customer Engagement Suite (CES) REST API. It adds entirely missing customer-managed tool types, exposes read-only platform-managed tool blocks, and resolves several missing attribute gaps in the existing tools.

Documentation

https://docs.cloud.google.com/customer-engagement-ai/conversational-agents/ps/reference/rest/v1/projects.locations.apps.tools#resource:-tool

Technical Details

• Added Missing Tools:
  • agentTool
  • fileSearchTool
  • widgetTool
• Exposed Read-Only (Output-Only) Tool Types:
  • remoteAgentTool
  • connectorTool
  • mcpTool
• Fixed Gaps in Existing Tools:
  • Added promptConfig with custom textPrompt and voicePrompt settings to googleSearchTool.
  • Added dataStoreSource and filterParameterBehavior to dataStoreTool (with mutual exclusivity conflicts: tags configured against engineSource).
• Resource Documentation & Note:
  • Added a docs.note block at the top of Tool.yaml detailing the relationship between google_ces_tool and google_ces_toolset.
  • Created 3 new example templates (ces_tool_agent_basic.tf.tmpl, ces_tool_file_search_basic.tf.tmpl, and ces_tool_widget_basic.tf.tmpl) to showcase the new tools.

Verification Results

• Code generation successful for both GA and Beta.
• Acceptance tests passed successfully for all newly implemented tools and documentation examples for both GA and beta

ces: added `agent_tool`, `file_search_tool`, and `widget_tool` support to the `google_ces_tool` resource

ces: added `prompt_config` to `google_search_tool` and `data_store_source` to `data_store_tool` in the `google_ces_tool` resource

ces: exposed `remote_agent_tool`, `connector_tool`, and `mcp_tool` as read-only (output-only) attributes in `google_ces_tool`

Derived from GoogleCloudPlatform/magic-modules#17758