Reusing `/api/v1` from Gitea UI Pages have pros and cons.
Pros:
1) Less code copy
Cons:
1) API/v1 have to support shared session with page requests.
2) You need to consider for each other when you want to change something about api/v1 or page.
This PR moves all dependencies to API/v1 from UI Pages.
Partially replace #16052
* Handle invalid issues
- When you hover over a issue reference, and the issue doesn't exist, it
will just hang on the loading animation.
- This patch fixes that by showing them the pop-up with a "Error
occured" message.
* Add I18N
* refactor
* fix comment for lint
* fix unit test for i18n
* fix unit test for i18n
* add comments
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>