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](70e98bb0-ecb9-4c4e-a89f-4a37d4e37f8e)

</details>

APNG:

<details>


![image](9055135b-5e2d-4152-bd72-596fcb7c6671)


![image](50364caf-f7f6-4241-a289-e485fe4cd582)

</details>

WebP (animated)

<details>


![image](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>

modules/repository/commits_test.go

@@ -6,6 +6,7 @@ package repository
 import (
 	"crypto/md5"
 	"fmt"
+	"strconv"
 	"testing"
 	"time"
 
@@ -136,13 +137,11 @@ func TestPushCommits_AvatarLink(t *testing.T) {
 	enableGravatar(t)
 
 	assert.Equal(t,
-		"https://secure.gravatar.com/avatar/ab53a2911ddf9b4817ac01ddcd3d975f?d=identicon&s=84",
+		"https://secure.gravatar.com/avatar/ab53a2911ddf9b4817ac01ddcd3d975f?d=identicon&s="+strconv.Itoa(28*setting.Avatar.RenderedSizeFactor),
 		pushCommits.AvatarLink(db.DefaultContext, "user2@example.com"))
 
 	assert.Equal(t,
-		"https://secure.gravatar.com/avatar/"+
-			fmt.Sprintf("%x", md5.Sum([]byte("nonexistent@example.com")))+
-			"?d=identicon&s=84",
+		fmt.Sprintf("https://secure.gravatar.com/avatar/%x?d=identicon&s=%d", md5.Sum([]byte("nonexistent@example.com")), 28*setting.Avatar.RenderedSizeFactor),
 		pushCommits.AvatarLink(db.DefaultContext, "nonexistent@example.com"))
 }