[feature] Add opt-in RSS feed for account's latest Public posts (#897)

* start adding rss functionality

* add gorilla/feeds dependency

* first bash at building rss feed
still needs work, this is an interim commit

* tidy up a bit

* add publicOnly option to GetAccountLastPosted

* implement rss endpoint

* fix test

* add initial user docs for rss

* update rss logo

* docs update

* add rssFeed to frontend

* feed -> feed.rss

* enableRSS

* increase rss logo size a lil bit

* add rss toggle

* move emojify to text package

* fiddle with rss feed formatting

* add Text field to test statuses

* move status to rss item to typeconverter

* update bun schema for enablerss

* simplify 304 checking

* assume account not rss

* update tests

* update swagger docs

* allow more characters in title, trim nicer

* update last posted to be more consistent

internal/api/client/account/accountupdate.go

@@ -110,6 +110,11 @@ import (
 //			Custom CSS to use when rendering this account's profile or statuses.
 //			String must be no more than 5,000 characters (~5kb).
 //		type: string
+//	-
+//		name: enable_rss
+//		in: formData
+//		description: Enable RSS feed for this account's Public posts at `/[username]/feed.rss`
+//		type: boolean
 //
 //	security:
 //	- OAuth2 Bearer:
@@ -202,7 +207,8 @@ func parseUpdateAccountForm(c *gin.Context) (*model.UpdateCredentialsRequest, er
 			form.Source.Language == nil &&
 			form.Source.StatusFormat == nil &&
 			form.FieldsAttributes == nil &&
-			form.CustomCSS == nil) {
+			form.CustomCSS == nil &&
+			form.EnableRSS == nil) {
 		return nil, errors.New("empty form submitted")
 	}