[feature] implement Vim-style "Join Lines" (Shift+J) shortcut #2

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

I would like to propose the addition of the Shift+J keyboard shortcut to the editor. This feature should emulate the standard Vim "Join Lines" behavior, allowing users to quickly merge the current line with the line directly below it.

Example
Current State:

console.log("Hello");
console.log("World");

Action: Press Shift+J while the cursor is on the first line.

Result:
console.log("Hello"); console.log("World");