Improve avatar uploading / resizing / compressing, remove Fomantic card module (#24653)

Fixes: #8972
Fixes: #24263

And I think it also (partially) fix #24263 (no need to convert) ,
because users could upload any supported image format if it isn't larger
than AVATAR_MAX_ORIGIN_SIZE


The main idea: 

* if the uploaded file size is not larger than AVATAR_MAX_ORIGIN_SIZE,
use the origin
* if the resized size is larger than the origin, use the origin

Screenshots:

JPG:

<details>


![image](https://github.com/go-gitea/gitea/assets/2114189/70e98bb0-ecb9-4c4e-a89f-4a37d4e37f8e)

</details>

APNG:

<details>


![image](https://github.com/go-gitea/gitea/assets/2114189/9055135b-5e2d-4152-bd72-596fcb7c6671)


![image](https://github.com/go-gitea/gitea/assets/2114189/50364caf-f7f6-4241-a289-e485fe4cd582)

</details>

WebP (animated)

<details>


![image](https://github.com/go-gitea/gitea/assets/2114189/f642eb85-498a-49a5-86bf-0a7b04089ae0)

</details>

The only exception: if a WebP image is larger than MaxOriginSize and it
is animated, then current `webp` package can't decode it, so only in
this case it isn't supported. IMO no need to support such case: why a
user would upload a 1MB animated webp as avatar? crazy .....

---------

Co-authored-by: silverwind <me@silverwind.io>

services/repository/avatar.go

@@ -6,7 +6,6 @@ package repository
 import (
 	"context"
 	"fmt"
-	"image/png"
 	"io"
 	"strconv"
 	"strings"
@@ -21,7 +20,7 @@ import (
 // UploadAvatar saves custom avatar for repository.
 // FIXME: split uploads to different subdirs in case we have massive number of repos.
 func UploadAvatar(ctx context.Context, repo *repo_model.Repository, data []byte) error {
-	m, err := avatar.Prepare(data)
+	avatarData, err := avatar.ProcessAvatarImage(data)
 	if err != nil {
 		return err
 	}
@@ -47,9 +46,7 @@ func UploadAvatar(ctx context.Context, repo *repo_model.Repository, data []byte)
 	}
 
 	if err := storage.SaveFrom(storage.RepoAvatars, repo.CustomAvatarRelativePath(), func(w io.Writer) error {
-		if err := png.Encode(w, *m); err != nil {
-			log.Error("Encode: %v", err)
-		}
+		_, err := w.Write(avatarData)
 		return err
 	}); err != nil {
 		return fmt.Errorf("UploadAvatar %s failed: Failed to remove old repo avatar %s: %w", repo.RepoPath(), newAvatar, err)