1. Introduce lightweight `fetch` wrapper functions that automatically
sets csfr token, content-type and use it in `RepoActionView.vue`.
2. Fix a specific issue on `RepoActionView.vue` where a fetch network
error is shortly visible during page reload sometimes. It can be
reproduced by F5-in in quick succession on the actions view page and was
also producing a red error box on the page.
Once approved, we can replace all current `fetch` uses in UI with this
in another PR.
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Co-authored-by: Giteabot <teabot@gitea.io>