Make all line discipline key bindings configurable (unbind/rebind Ctrl-C, etc.)

# Description of the new feature/enhancement

Some people don't like Ctrl-C, etc., and would like to have such keybindings be configurable and use macro keys, or similar instead. It's possible to do so and would clean up and centralize lots of our hardcoded assumptions.

# Proposed technical implementation details (optional)

TBD. [TerminalInput](https://github.com/microsoft/terminal/blob/0f41851e67614dd3f78d399f91d4636087c3179c/src/terminal/input/terminalInput.cpp) has them hardcoded right now, which would need to be configurable. Ctrl-C and more are handled in many more parts throughout OpenConsole and Windows Terminal which would all need to be centralized.

Start by reading src/terminal/input/terminalInput.cpp, where the issue says line-discipline key bindings are hardcoded, then trace the other Ctrl-C and related handling mentioned across OpenConsole and Windows Terminal. The work is complete when these bindings are centralized and configurable, including unbinding, rebinding, and macro-key use.

Written by the indexing model from the issue text.