feat: apply additionalTextEdits after completion

See https://microsoft.github.io/language-server-protocol/specification#textDocument_completion

    /**
     * An optional array of additional text edits that are applied when
     * selecting this completion. Edits must not overlap (including the same
     * insert position) with the main edit nor with themselves.
     *
     * Additional text edits should be used to change text unrelated to the
     * current cursor position (for example adding an import statement at the
     * top of the file if the completion item will insert an unqualified type).
     */

atom-community / atom-languageclient

feat: apply additionalTextEdits after completion #162