Several fixes for mobile UI (go-gitea#25634)

Backport go-gitea#25634

Resolves go-gitea#25622

<details>
<summary>Screenshots</summary>

![Bildschirmfoto vom 2023-07-02
20-47-34](https://github.com/go-gitea/gitea/assets/47871822/a8a0bff6-9ae3-48f3-b008-00c196a3f8fd)
![Bildschirmfoto vom 2023-07-02
20-47-45](https://github.com/go-gitea/gitea/assets/47871822/172a0021-af74-4690-aa67-0e66688ce733)
![Bildschirmfoto vom 2023-07-02
20-48-37](https://github.com/go-gitea/gitea/assets/47871822/14572ebd-0106-4c8a-ba27-b6b631375ee6)
![Bildschirmfoto vom 2023-07-02
20-49-08](https://github.com/go-gitea/gitea/assets/47871822/7c0ba3aa-1712-482c-aae9-13394dbdaf8a)
![Bildschirmfoto vom 2023-07-02
20-50-28](https://github.com/go-gitea/gitea/assets/47871822/8bd68e26-099a-4abd-8817-16d52af13167)
![Bildschirmfoto vom 2023-07-02
20-51-46](https://github.com/go-gitea/gitea/assets/47871822/3beab8c6-3747-4829-be50-bafaed11000c)
![Bildschirmfoto vom 2023-07-02
20-54-12](https://github.com/go-gitea/gitea/assets/47871822/51f82ef3-a32c-4c27-9056-e8711ed469cc)

</details>

---------

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

web_src/css/repo.css

@@ -3147,6 +3147,14 @@ tbody.commit-list {
  flex-wrap: wrap;
 }
 
+.commits-table .commits-table-right form {
+ display: flex;
+ align-items: center;
+ gap: 0.75em;
+ justify-content: center;
+ flex-wrap: wrap;
+}
+
 @media (max-width: 767.98px) {
  .repository.file.list #repo-files-table .entry,
  .repository.file.list #repo-files-table .commit-list {