Do a large chunk of the move to go

This commit moves a huge chunk of the code to go. The TODO.md document
indicates what is left to be done.

internal/execx/compose.go

@@ -0,0 +1,11 @@
+package execx
+
+import (
+	"github.com/tkw1536/goprogram/stream"
+)
+
+// Compose runs a docker-compose command in a specific directory, with the provided arguments and streams.
+// It then waits for the process to exit, and returns the exit code.
+func Compose(io stream.IOStream, workdir string, args ...string) int {
+	return Exec(io, workdir, "docker", append([]string{"compose"}, args...)...)
+}