Ollama node enhancement

[b3by]

Description

This PR introduces changes to the prompter_ollama plugin node, including:

• keep alive, to prevent ollama from unloading the model from memory;
• adding a setup file to store system prompts;
• enabling or disabling thinking for supporting models

PR type

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Test update
• Build/CI configuration change
• Other (please describe):

Key modifications and changes

New features for prompter_ollama.