Provide the workbench moderation form from node/%/latest with a block

To be honest, I am not sure if it should be a global setting or a per-content-type setting really. I guess its two things. One: hiding the form for some content types and Two: giving us the form as a block.

+++ b/src/Plugin/Block/WorkbenchModerationLatestBlock.php
@@ -0,0 +1,105 @@
+ * @Block(
+ *   id = "workbench_moderation_latest_block",
+ *   admin_label = @Translation("Latest version")
+ * )

You can inherit the node context and you may not need the RouteMatchInterface.

 * @Block(
 *   id = "workbench_moderation_latest_block",
 *   admin_label = @Translation("Latest version"),
 *   context = {
 *     "node" = @ContextDefinition("entity:node", label = @Translation("Node"))
 *   }
 * )
 *
 */

+++ b/src/Plugin/Block/WorkbenchModerationLatestBlock.php
@@ -0,0 +1,105 @@
+    if ($node = $this->routeMatch->getParameter('node')) {

$node = $this->getContextValue('node');

If we're going for clarity with this re-title...

One issue I am finding in testing this: We redirect users to node/%/latest whenever a [insert_state_here] is transitioned to "draft" -- however, if there is no published version of the node, then the draft shows up at node/% -- and you get an access denied error trying to visit node/%/latest

Example to try:

1. Add a new moderation state called "pre-draft"
2. Add transitions for moving content, you'll need "pre-draft to pre-draft" (for creating new content) and "pre-draft to draft" (for moving pre-draft to draft, obviously)
3. Set "pre-draft" as the default moderation state for new Article nodes
4. Create a new Article (should be in "pre-draft" state)
5. Use the Moderation form block to transition from pre-draft to draft
6. Note the redirect to node/%/latest upon submitting this state change

Edit: This is likely happening because the original form assumes one is always at node/%/latest where it originally lived before we introduced this more flexible block that could occur just about anywhere, regardless of current state.