New Event Semantic and Major Improvements

[mdapena]

Initial Checks

• The code compiles successfully without any errors or warnings.
• I have personally tested these changes on my local environment.
• I have ensured that relevant documentation has been added or updated.
• I adhere to the project structure and code standards defined in the documentation.
• My code follows the established coding style guidelines.
• I have added tests for the new code (if applicable).
• All existing tests have passed successfully.

Description

This PR introduces significant improvements to Pyventus' event handling system, including a new event semantic model and extended dataclass support. Key changes focus on removing the base Event class, enhancing sync event handling, and strengthening documentation. Release Notes:

Breaking Changes

• Removed the base Event class due to improved event semantics and unnecessary redundancy.
• Renamed the get_event_registry() method of EventLinker to get_registry().
• Renamed the __event_registry inner property of EventLinker to __registry.
• Renamed the get_events_by_handler() method of EventLinker to get_event_handlers_by_events().
• Renamed the get_handlers_by_events() method of EventLinker to get_event_handlers_by_events().
• Renamed the protected method _executor_callback() of the ExecutorEventEmitter to _callback().
• Renamed the task name of CeleryEventEmitter from _executor to pyventus_executor to avoid collisions with other
  task names.

Added

• Added __slots__ to EventLinkageWrapper class for more efficient memory usage.
• Extended support for subscription and emission of any dataclass object, removing the limitation of only Event
  subclasses.
• Added the force_async parameter to the EventHandler class and EventLinker subscription methods to be able to
  optimize the execution of sync callbacks based on their workload.
• Introduced a new event semantic where the Python ... (Ellipsis) is now used to refer to all events on a
  subscription, like the onAny() method but with a Pythonic syntax.
• Added the mkdocs-material social cards plugin, which provides a preview of the documentation content when shared on
  social media platforms.

Changed

• Standardized the order of static methods, class methods, and instance methods for improved readability.
• Applied Python best practices to optimize the methods within the EventLinker and EventEmitter classes.
• Improved validation of variable instances in the event emitters, EventLinker, and EventHandler.
• Updated and improved the test suite to ensure accurate validation and consistency.
• Enabled creation date for the mkdocs git-revision-date-localized plugin.
• Replaced the mkdocs git-authors plugin with the git-committers plugin.
• Updated and improved the package description.
• Updated the tutorial section to incorporate recent changes.
• Enhanced the documentation index page and README file with new examples and better descriptions to showcase the unique
  features of Pyventus.

Removed

• Removed the default value of the once flag in the EventHandler class.

Fixed

• Fixed and standardized all package docstrings and code comments for consistency and clarity.
• Addressed minor errors and details in the documentation.