feat: OllamaChatGenerator update tools param to ToolsType

[vblagoje]

Why:

Adopts Haystack's ToolsType to enable flexible tool composition, developers can now mix individual Tool objects and Toolset instances in a single list

part of:

• Update Chat Generators to support mixed Tools and Toolsets Update Chat Generators to support mixed Tools and Toolsets #2409

What:

• Updated tools parameter from Union[List[Tool], Toolset] to ToolsType in constructor and all methods
• Replaced manual isinstance(tools, Toolset) checks with flatten_tools_or_toolsets() utility
• Haystack dependency to 2.19.0 for ToolsType support
• Added tests for mixed tool collection initialization and request parameter formatting

How can it be used:

from haystack.tools import Tool, Toolset
from haystack_integrations.components.generators.ollama.chat import OllamaChatGenerator

weather_tool = Tool(name="weather", ...)
population_toolset = Toolset([...])

# NEW: Mix Tool and Toolset freely
generator = OllamaChatGenerator(tools=[weather_tool, population_toolset])

How did you test it:

• Unit tests verify mixed tool initialization and correct Ollama tools formatting
• Backward compatibility validated for existing patterns (list of tools, single toolset)
• Integration test test_live_run_with_mixed_tools() demonstrates end-to-end LLM tool invocation from mixed collections

Notes for the reviewer:

• Centralizes tool normalization logic with flatten_tools_or_toolsets()—eliminates duplicate handling code
• Fully backward compatible; no migration needed
• Ollama-specific: Tools are properly serialized to Ollama's expected format with {"type": "function", "function": {**tool.tool_spec}}
• Added comprehensive test coverage for mixed tool scenarios including both unit and integration tests

[vblagoje]

@anakin87 can you also please look at these files?

[anakin87]

@anakin87 can you also please look at these files?

Which files?

[vblagoje]

@anakin87 can you also please look at these files?

Which files?

Sorry I meant this PR 🤦

[anakin87]

Looks good