fix: install snapd from edge inside build environments

[mr-cal]

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1. Install snapd from edge inside build environments
2. Update spread tests to exercise build environments (two tests use lxd, one uses destructive-mode)

Note:
Installing snapd from edge exposed a minor bug in craft-providers 1.20.1. However, that bug was mercifully fixed in the 1.19.3 hotfix (which was released and merged to main after 1.20.1 and there hasn't been a release on main since). So To get this prototype out the door, I'm just pointing to main for craft-providers and I'll do a release soon.

[syu-w]

snapd edge only for this test or you want to use it for all builds? Or the components support needs it?

[mr-cal]

pyright failure fixed in #4512, which has not been cherry-picked to this branch

[mr-cal]

snapd edge only for this test or you want to use it for all builds? Or the components support needs it?

It's only needed only when components are being built.

I could set the snapd channel based on whether components are being built.

I decided to do the simple approach because by the time this is ready to merge into main, snapd will support components on latest/stable and I'll be able remove this from the experimental feature branch.