Add setting to always use remote builder, even when docker is running

[mrkurt]

Docker can be problematic on m1 Macs, and there are some cases where it makes sense to have Docker running locally but use remote builds for Fly.

fly deploy --remote-only works just fine, but it would be nice to be able to configure a system to default to --remote-only. Can we have a FLY_BUILD_REMOTE_ONLY environment variable for this?

[jsierles]

Why not make remote the default?

[mik3y]

Other than the M1 issue, I've found a couple situations where I always prefer remote build: e.g. working from a plane, rural/crappy internet, etc.

Remote is preferable here because of Docker Stuff: while I might only have a few kb of code (docker context), the build itself might suck down gigs of layers to get there.

I'd be happy to submit a patch for this - could use a pointer or preference on approach, if it's a viable idea. Is exposing an env var the way to go..? (Is there an app-unspecific .flyctrlrc where this kind of preference could fit the bill..?)

[kzys]

Resolving? It is default now.