Pretty much everything has been changed and touched.

Increased modularity and thus improved extendability, flexibility, testability and component reusability.

Context is finding its way in. There is for example h.ExecContext(ctx, ...) and h.Connect(ctx).

Short summary of changes to usage:

Exec.Sudo() is gone.

// before:
h.Exec("command", exec.Sudo())
h.SudoFsys().OpenFile(...)
// after:
h.Sudo().Exec("command")
h.Sudo().FS().OpenFile(...)

There's no more "Execf".

// before
h.Execf("command %s", shellescape.Quote(path))
// after
h.Exec(sh.Command("command", path)) // path is automatically quoted like in os/exec.

Configurers are gone. You may still need to implement them for your own usecases, but they're no longer in rig. Instead, the functionality has been spread out to different components and more stdlib os resembling functionality bundled with the fs.FS implementation in rig/remotefs.

// before
h.Configurer.WriteFile("foo.txt", "content")
// after
h.FS().WriteFile("foo", []byte("content"), 0o600)

// before
h.Configurer.InstallPackages(h, "curl", "iptables")
// after
h.Sudo().PackageManager().Install(context.Background(), "curl", "iptables")

// before
h.Configurer.StartService(h, "foo")
// after
h.Service("foo").Start(context.Background())

A great chunk of replicated logic in each of the protocol client implementations was moved to a centralized cmd.Executor. The protocols now only need to implement a single StartProcess function, all of the output capturing, input relaying and so on is done in the executor.

There are a number of io.Writers and io.Readers now used internally for things that were done with string manipulations before. Many of these are reusable for other stuff.

TODO - this PR does not include much refactoring for the connection setup stuff, which has become quite difficult to maintain due to its complexity, especially the SSH. That will be addressed in a separate PR before a final 2.0.0 is tagged.