Should return CodeActions[] instead of Commands[] if client supports code action literals

[fbricon]

the server should check if the client supports codeActions, by checking if clientCapabilities.getTextDocument().getCodeAction().getCodeActionLiteralSupport() != null.
If codeActionLiteralSupport is supported, then return CodeActions. Else, return commands. See https://github.com/Microsoft/language-server-protocol/blob/gh-pages/specification.md#code-action-request-leftwards_arrow_with_hook (available since protocol 3.8.0).

We then might be able to phase out java.apply.workspaceEdit support in the future

[snjeza]

A duplicate of #800

[fbricon]

closing as duplicate of #800