Move 'Organize Imports' to be a CodeAction

[mjbvz]

Hi, I'm on the vs code team. We recently introduced a more standardized way to implement Organize Imports with code actions (microsoft/vscode#47845). Using code actions instead of commands allows vs code to provide a more standard and consistent experience across languages. We are also using the new code action based implementation to power new UI like the Source Action context menu

Our JavaScript and TypeScript organize imports feature has already been migrated from a command to a code action: microsoft/vscode#46647 I suggest that the Java extension do the same so that the developer experinace is more consistent and to prevent conflicts with other extensions. This is currently blocked by microsoft/language-server-protocol#389

[fbricon]

Now that eclipse-jdtls/eclipse.jdt.ls#796 was merged, this should be doable.
@mjbvz do you know if it's possible to bind keys to a code action?

[fbricon]

The Organize imports command is no longer available directly at the root of the context menu, via the Source actions... menu:

The Shift+Alt+o shortcut is still working as before.