2nd gen overhaul

[jhuleatt]

• Rearrange samples. Instead of 1st gen samples being at root with 2nd gen in a folder, all 2nd gen samples are in a folder called "Node", and 1st gen are in a folder called "Node-1st-gen". Quickstart-type samples have been moved into quickstart folders.
• Update pnpm and typescript
• Update all runtimes from Node 16 to Node 18 (current recommended runtime)
• Update common deps: firebase-functions, firebase-admin, firebase-functions-test, eslint, typescript
• Re-organize main README to list each available language of a sample
• Update CI

[hack-r]

Thanks for your updates! Do you have a 2nd or 3rd gen version of the OCR / Vision function? I didn't see it.