internal/params: relocate from package container

This does not make sense as part of the public API, so make it internal.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/container_test.go

@@ -26,6 +26,7 @@ import (
 	"hakurei.app/fhs"
 	"hakurei.app/hst"
 	"hakurei.app/internal/info"
+	"hakurei.app/internal/params"
 	"hakurei.app/ldd"
 	"hakurei.app/message"
 	"hakurei.app/vfs"
@@ -84,9 +85,9 @@ func TestStartError(t *testing.T) {
 		{"params env", &container.StartError{
 			Fatal: true,
 			Step:  "set up params stream",
-			Err:   container.ErrReceiveEnv,
+			Err:   params.ErrReceiveEnv,
 		}, "set up params stream: environment variable not set",
-			container.ErrReceiveEnv, syscall.EBADF,
+			params.ErrReceiveEnv, syscall.EBADF,
 			"cannot set up params stream: environment variable not set"},
 
 		{"params", &container.StartError{