FIX: Replace censored watched word consistently (#12486)

Applying oneboxes and replacing censored watched words does not happen
in a strict order which often lead to inconsistencies. This commit
fixes the behavior and will never censor oneboxes.

To make it always censor oneboxes implies significant changes to the
PrettyText pipeline.

app/assets/javascripts/pretty-text/engines/discourse-markdown/censored.js

@@ -3,6 +3,10 @@ import { censorFn } from "pretty-text/censored-words";
 function recurse(tokens, apply) {
   let i;
   for (i = 0; i < tokens.length; i++) {
+    if (tokens[i].type === "html_raw" && tokens[i].onebox) {
+      continue;
+    }
+
     apply(tokens[i]);
     if (tokens[i].children) {
       recurse(tokens[i].children, apply);

app/assets/javascripts/pretty-text/engines/discourse-markdown/onebox.js

@@ -81,6 +81,7 @@ function applyOnebox(state, silent) {
               child.type = "html_raw";
               child.content = cached;
               child.inline = true;
+              child.onebox = true;
 
               text.type = "html_raw";
               text.content = "";