Move tree-sitter as a selectable analysis back-end to a `commons` module and use functionalities without exposing it in the core.

[rahlk]

Description:
Currently, the tool allows users to select Tree-sitter as an analysis backend through the core module. However, to streamline the architecture and encapsulate implementation details, Tree-sitter should be moved to a commons module. This refactoring will allow the tool to leverage Tree-sitter's functionalities internally without exposing it as a configurable option at the core level.

Additionally, CodeQL will be removed and therefore there is no longer a need to expose tree-sitter this way.

Acceptance Criteria:

1. Tree-sitter is moved to a commons module, encapsulating all Tree-sitter-related logic.
2. The core module no longer exposes Tree-sitter as a selectable analysis backend.
3. Update all relevant documentation and code examples to reflect these changes.

Current Code (Before):

if self.analysis_backend in [AnalysisEngine.CODEQL, AnalysisEngine.TREESITTER]:
    # Perform analysis

Proposed Code (After):

from cldk.analysis.commons.treesitter import TreeSitterEngine

# Tree-sitter is now the fallback backend, no need for conditional checks

Steps to Implement:

1. Create a commons module to house the Tree-sitter engine and related utilities.
2. Refactor the core module to remove references to Tree-sitter as an exposed option.
3. Update the initialization logic to use Tree-sitter as the default backend.
4. Update documentation to reflect these structural changes.

Benefits:

• Simplifies the core module by reducing unnecessary exposure of backend configurations.
• Improves maintainability by isolating Tree-sitter-specific logic.

Environment:

• OS: Fedora 41
• Java Version: 21
• Tool Version: 0.4.0 (and lower)