Environment definitions starter pack

[itowlson]

This provides TOML environment definitions for Spin 3.2 and 3.4. (It will also need a definition for 3.5, once #3295 is agreed.)

Proposed plan of attack:

• Once Workflow for publishing spin:up WIT package #3300 merges, we can run that against the 3.4 and 3.2 branches to get those WITs into the default spinframework.dev registry.
• Then we can test these TOMLs using local files against all of our templates and any known good applications. This is important because during dev I ran into problems with apps that targeted older worlds and we want to make sure that these (within reason) do not give spurious errors. My dev test suggested that we might need to retrofit some compat stuff to the top level worlds which I really hope we don't have to do but well this is where we find out I guess.
• Then we can merge them. mumble mumble automation mumble CI mumble muttered cursing
• Then we can push them to the default OCI registry.
• Then we can test them again using just env names instead of file references. Which will work first time and will produce no mysterious inconsistencies, none do you hear me, but you know, good form.
• And then we can tell people about them!

[itowlson]

#3293 had an open question about where we want to keep these but it's not had much traction so I'm parking them here for now but if people have other preferences then whatever