luci-app-firewall: i18n string context

[AndyChiang888]

Pull Request details

Description

i18n string context

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Tested on

OpenWrt version: SNAPSHOT
LuCI version: master
Web browser: Chrome

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Checklist

• This PR is not from my main or master branch 💩, but a separate branch. ✅
• Each commit has a valid ✒️ Signed-off-by: <my@email.address> row (via git commit --signoff).
• Each commit and PR title has a valid 📝 <package name>: title first line subject for packages.
• Incremented 🆙 any PKG_VERSION in the Makefile.
• (Optional) Includes what Issue it closes (e.g. openwrt/luci#issue-number).
• (Optional) Includes what it depends on (e.g. openwrt/packages#pr-number in sister repo).