feat(genai): add ToolFunctionCallingConfigWithText sample and standarize ToolFunctionDescriptionWithText sample

[Kef131]

Description

Fixes #
b/530303154

• Standardized ToolFunctionDescriptionWithText.java to use the get_current_weather function declaration for consistency across SDK samples.
• Created ToolFunctionCallingConfigWithText.java to demonstrate using FunctionCallingConfig (mode ANY with allowedFunctionNames) for forced function calling with the Google Gen AI SDK (google-genai).
• Updated ToolsIT.java to include unit test coverage for the new and updated samples.

Checklist

• I have followed Sample Format Guide
• pom.xml parent set to latest shared-configuration
• Appropriate changes to README are included in PR
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• Tests pass: mvn clean verify required
• Lint passes: mvn -P lint checkstyle:check required
• Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request introduces a new code sample, ToolFunctionCallingConfigWithText.java, to demonstrate forcing a specific function call using ToolConfig. It also updates ToolFunctionDescriptionWithText.java to use a simpler weather-based function calling example instead of the album sales example, and updates the integration tests accordingly. The feedback suggests improving the schema definition in the new sample by explicitly marking fields as required to ensure consistent structured output from the model.