OPSCANS: rewrite for new site

[AwkwardPeak7]

closes #149

• package name changed from all.opscans to en.opscans
• version reset as it's now a new package

Checklist:

• [x] Updated extVersionCode value in build.gradle for individual extensions
• [ ] Updated overrideVersionCode or baseVersionCode as needed for all multisrc extensions
• [x] Referenced all related issues in the PR body (e.g. "Closes #xyz")
• [ ] Added the isNsfw = true flag in build.gradle when appropriate
• [x] Have not changed source names
• [ ] Have explicitly kept the id if a source's name or language were changed
• [x] Have tested the modifications by compiling and running the extension through Android Studio
• [ ] Have removed web_hi_res_512.png when adding a new extension