Refactor issue assignment bot workflow

[cpholguera]

This pull request enhances the issue-assignment-bot workflow by adding detailed logging, improving comment classification logic, and making the bot's behavior more robust and transparent. The changes focus on improving traceability, debugging, and clarity in how assignment requests and acceptance are handled.

Logging and debugging improvements:

• Added extensive logging throughout the workflow steps to capture key event details, classification decisions, and API call results, making it easier to trace and debug the bot's behavior. [1] [2] [3] [4] [5]

Comment classification and assignment request handling:

• Improved comment normalization and matching for the acceptance phrase, ensuring case consistency and handling formatting variations. Added logging for classification outcomes and reasons for skipping requests. [1] [2]
• Enhanced assignment request logic to check for prior bot prompts and avoid duplicate guideline comments; logs when a user has already been prompted.

Acceptance handling and label management:

• Refined acceptance handling to verify prior bot prompts before labeling, and added logging for label application and confirmation comment creation.

Code and naming consistency:

• Updated job and step names for consistency (handle-assignment-request to handle_assignment_request) and clarified variable names throughout the workflow.

Permissions and configuration:

• Added contents: read permission to the workflow to ensure proper access for bot actions.