[ENHANCEMENT] Reserve the key `library` exclusively for configuring Robot Framework libraries in the robot.toml file

[d-biehl]

Background: Configuring libraries directly in test suites using the Library statement and arguments can become complex, especially with libraries like Browser. Centralizing this configuration in robot.toml would simplify management and improve maintainability.

Proposed Solution:

• Reserve library in robot.toml for library configurations, similar to the tool section in pyproject.toml.
• Leverage the existing profile support in robot.toml to allow library configurations to be defined per profile. This enables different library setups for environments like testing, development, or production.
• Ensure consistency across tools like CLI and VSCode when handling library configurations and profiles.

Benefits:

• Cleaner, more maintainable configuration for complex libraries.
• Centralized management of libraries, reducing clutter in test suites.
• Profiles enable flexible library configurations for different environments.
• Familiar structure for Python developers using pyproject.toml.

Impact:

• Documentation and tool updates may be required.
• Ensure backward compatibility with current library configurations.