[feature] Fetch + display custom emoji in statuses from remote instances (#807)

* start implementing remote emoji fetcher

* update status where pk

* aaa

* tidy up a little

* check size limits for emojis

* thank you linter, i love you <3

* update swagger docs

* add emoji dereference test

* make emoji max sizes configurable

* normalize db.ErrAlreadyExists

internal/config/validate.go

@@ -67,6 +67,14 @@ func Validate() error {
 		errs = append(errs, fmt.Errorf("%s must be set", WebAssetBaseDirFlag()))
 	}
 
+	if m := GetMediaEmojiLocalMaxSize(); m < 0 {
+		errs = append(errs, fmt.Errorf("%s must not be less than 0", MediaEmojiLocalMaxSizeFlag()))
+	}
+
+	if m := GetMediaEmojiRemoteMaxSize(); m < 0 {
+		errs = append(errs, fmt.Errorf("%s must not be less than 0", MediaEmojiRemoteMaxSizeFlag()))
+	}
+
 	if len(errs) > 0 {
 		errStrings := []string{}
 		for _, err := range errs {