I'm familiar with how to move a line up or down in other editors, like Atom and Sublime.
How is this done in Visual Studio Code for Mac?
In Visual Studio Code for Mac...
To move a line UP: ⌥+↑ (alt + up arrow key)
To move a line DOWN: ⌥+↓ (alt + down arrow key)
See here for a reference on Basic Editing Key Bindings in Visual Studio Code.
In Visual Studio Code for Mac for me it is:
To move a line UP: ⌥+shift+↑ (alt + shift + up arrow keys)
To move a line DOWN: ⌥+shift+↓ (alt + shift + arrow down keys)
I do have IntelliJ IDEA Keybindings installed.