[feature] Parse content warning to HTML, serialize via client API as plaintext (#3876)

* [feature] Parse content warning as HTML, serialize via API to plaintext

* tidy up some cruft

* whoops

* oops

* i'm da joker baybee

* clemency muy lorde

* rename some of the text functions for clarity

* jiggle the opts

* fiddle de deee

* hopefully the last test fix i ever have to do in my beautiful life

internal/processing/status/create.go

@@ -189,6 +189,13 @@ func (p *Processor) Create(
 		PendingApproval: util.Ptr(false),
 	}
 
+	// Only store ContentWarningText if the parsed
+	// result is different from the given SpoilerText,
+	// otherwise skip to avoid duplicating db columns.
+	if content.ContentWarning != form.SpoilerText {
+		status.ContentWarningText = form.SpoilerText
+	}
+
 	if backfill {
 		// Ensure backfilled status contains no
 		// mentions to anyone other than author.