chore(*): migrate examples/templates/tests to Spin manifest v2

[vdice]

Updates apps under examples, templates and test to use Spin manifest v2

While updating and testing, I also:

• Updated READMEs, including, where applicable:
  • removing use of --follow-all on spin up
  • adding npm install prior to spin build (avoids the spin build -> 'would you like to install webpack?' -> 'yes' -> error -> spin build -> success)
  • updating the ts/planetscale example README.md which was incorrect
• Updated strings (eg lots of spin-http-js turned into a more specific value)
• Updated outbound http examples to use our in-house random data generator (https://random-data-api.fermyon.app)

Closes https://github.com/fermyon/spin-js-sdk/issues/203

Note: Should not be merged until Spin 2.0 is released. I've placed this in Draft due to this, but reviews/feedback appreciated in the meantime. This can be merged when ready per https://github.com/fermyon/spin-js-sdk/pull/206/commits/f3410b29e7d31b7ce92aeddfb9751cd447af8ba3