[feature] Allow user to choose "gallery" style layout for web view of profile (#3917)

* [feature] Allow user to choose "gallery" style web layout

* find a bug and squish it up and all day long you'll have good luck

* just a sec

* [performance] reindex public timeline + tinker with query a bit

* fiddling

* should be good now

* last bit of finagling, i'm done now i prommy

* panic normally

internal/processing/account/update.go

@@ -294,6 +294,18 @@ func (p *Processor) Update(ctx context.Context, account *gtsmodel.Account, form
 		settingsColumns = append(settingsColumns, "web_visibility")
 	}
 
+	if form.WebLayout != nil {
+		webLayout := gtsmodel.ParseWebLayout(*form.WebLayout)
+		if webLayout == gtsmodel.WebLayoutUnknown {
+			const text = "web_layout must be one of microblog or gallery"
+			err := errors.New(text)
+			return nil, gtserror.NewErrorBadRequest(err, text)
+		}
+
+		account.Settings.WebLayout = webLayout
+		settingsColumns = append(settingsColumns, "web_layout")
+	}
+
 	// We've parsed + set everything, do
 	// necessary database updates now.