[nix] ensure nix version is >= 2.12 (#1700)

## Summary

Ensures that the nix used is >= 2.12 which is the minimum version we
support.
Our CICD tests run this version, and I believe so does @mohsenari.

I considered renaming the function to `ensureSupportedNixInstalled` but
decided against it. The current name is good enough, given the
function's scope
and location in the package.

## How was it tested?

ran `devbox shell` which results in this function being called.
Toggled the condition to trigger the error to verify it prints as we
want.

Author: savil

internal/boxcli/setup.go

@@ -4,13 +4,15 @@
 package boxcli
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/samber/lo"
 	"github.com/spf13/cobra"
-
+	"go.jetpack.io/devbox/internal/boxcli/usererr"
 	"go.jetpack.io/devbox/internal/nix"
 	"go.jetpack.io/devbox/internal/ux"
+	"go.jetpack.io/devbox/internal/vercheck"
 )
 
 const nixDaemonFlag = "daemon"
@@ -47,8 +49,22 @@ func runInstallNixCmd(cmd *cobra.Command) error {
 	return nix.Install(cmd.ErrOrStderr(), nixDaemonFlagVal(cmd)())
 }
 
+// ensureNixInstalled verifies that nix is installed and that it is of a supported version
 func ensureNixInstalled(cmd *cobra.Command, _args []string) error {
-	return nix.EnsureNixInstalled(cmd.ErrOrStderr(), nixDaemonFlagVal(cmd))
+	if err := nix.EnsureNixInstalled(cmd.ErrOrStderr(), nixDaemonFlagVal(cmd)); err != nil {
+		return err
+	}
+
+	ver, err := nix.Version()
+	if err != nil {
+		return fmt.Errorf("failed to get nix version: %w", err)
+	}
+
+	// ensure minimum nix version installed
+	if vercheck.SemverCompare(ver, "2.12.0") < 0 {
+		return usererr.New("Devbox requires nix of version >= 2.12. Your version is %s. Please upgrade nix and try again.\n", ver)
+	}
+	return nil
 }
 
 // We return a closure to avoid printing the warning every time and just