Add upload button

[vincerubinetti]

@FaboBence Please test the upload feature in the Netlify preview link below.

• move "insufficient file" error to top of create pr script, so the error is discovered early, before branch is created
• re-run update.ts script to fill in more lesson full titles
• fix bug where submitting empty files would throw error
• add ability to upload previously downloaded zip
• make more comprehensive pre-populated issue links
• add "view raw json" button with link to line number
• fix case sensitivity bug in homepage lesson name search

[netlify]

✅ Deploy Preview for translate3b1b ready!

Name	Link
🔨 Latest commit	881f223
🔍 Latest deploy log	https://app.netlify.com/sites/translate3b1b/deploys/65f06cf9ab09ce0008f42776
😎 Deploy Preview	https://deploy-preview-367--translate3b1b.netlify.app
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[FaboBence]

I have tested the described functionality with main focus on the ZIP uploads. It's working well!

[3b1b]

It looks reasonable to me, and appears to work when I test it.

[3b1b]

Any objection if I merge?

[vincerubinetti]

Good to go