Misc improvements

[Sv443]

• [x] Improve /reminder
  • [x] Private reminders
  • [x] Fix double or even more expiration messages
  • [x] Fix reminders sometimes not sending expiration message
• [x] Improve /translate
  • [x] Fix translations with <2 sentences
  • [x] Add input_language arg
  • [x] Slightly increase performance
• [x] Fix API URLs
• [x] Duration calculation in @utils/time.ts
• [x] Consolidated common emojis into @utils/emojis.ts
• [x] Add env variable to add a prefix for distinguishing commands better
• [x] License the repo #70
• [x] Misc small fixes here and there idr