Support X11 primary selection buffer in inputs

This affects Linux users who make use of the primary selection buffer.

Related: https://github.com/microsoft/vscode/issues/130208

Normally you can select something, and then you can paste your most recent selection by middle clicking. It seems like whenever you open an input, eg Command Palette or the File Picker, the contents of the input are considered as a "selection" by the OS so overwrite the primary selection buffer.

Eg, say you are on a website which says "Run the foo command from the command palette". You select "foo", switch to VS Code. Run command palette, and middle click expecting it to paste "foo", however, instead it pastes ">".