Refactor Channel Class Hierarchy for Enhanced Flexibility and Consistency

[jianan1104]

This pull request introduces a significant refactor to the Channel class hierarchy in the Netmiko library. The primary goal of these changes is to enhance code flexibility, readability, and maintainability. Here's a summary of the key modifications:

1. Unified Channel Base Class Constructor:

   • The base Channel class now includes a constructor that initializes the remote_conn and encoding attributes. This standardizes the way these attributes are handled across different channel types (SSH, Telnet, and Serial).
   • By doing this, we reduce redundancy and potential inconsistencies in how different channel types are instantiated.

2. Type Hinting for remote_conn:

   • Introduced explicit type hinting for the remote_conn attribute in each subclass, clarifying the specific connection type each channel is working with.
   • This change improves code clarity and assists in static type checking, making the codebase more robust and easier to understand.

3. Removed Unused Comments and Code:

   • Removed commented-out abstract methods in the base Channel class that are not currently implemented or required. This helps in focusing on the actual functionalities provided by the channel classes.
   • This cleanup aids in reducing distractions and potential confusion about the intended use and capabilities of the Channel class.

4. Exception Handling Consistency:

   • Ensured consistent handling of scenarios where there is no active channel across all channel types. This consistency in exception handling makes the code behavior more predictable and easier to debug.

5. Use of super().__init__():

   • Used super().__init__() in the subclasses to call the base class constructor. This ensures that initialization is handled consistently and follows proper object-oriented practices.

By making these changes, we aim to make the code more efficient, maintainable, and consistent, aligning with best practices in Python development. This refactor should have no impact on the existing functionality of the Netmiko library but sets a stronger foundation for future enhancements and maintenance.

[ktbyers]

Doesn't seem worth worrying about...so I am just going to close this.