feat: print warning on some unsupported compose features (#288)

* feat: error on unsupported compose features

This implements a check for the unimplemented features of the uncloud
support matrix and points to the matrix in the error.

Fixes: #237

This redos #277, as I messed up my branch, (basically rebase gone
wrong).

Signed-off-by: Miek Gieben <miek@miek.nl>

* Fix tests by capturing stderr

The error should be nil, but we _do_ want to know if the user saw an
warning. Redirect stderr to capture this as the error is emited by
printing to stderr.

Signed-off-by: Miek Gieben <miek@miek.nl>

---------

Signed-off-by: Miek Gieben <miek@miek.nl>

pkg/client/compose/project.go

@@ -12,6 +12,7 @@ import (
 	"github.com/compose-spec/compose-go/v2/transform"
 	"github.com/compose-spec/compose-go/v2/tree"
 	"github.com/compose-spec/compose-go/v2/types"
+	"github.com/psviderski/uncloud/internal/cli/tui"
 	"github.com/psviderski/uncloud/pkg/api"
 )
 
@@ -66,6 +67,10 @@ func LoadProject(ctx context.Context, paths []string, opts ...composecli.Project
 		return nil, err
 	}
 
+	if err = validateServicesFeatures(project); err != nil {
+		tui.PrintWarning(err.Error())
+	}
+
 	// Process image templates in services to expand Go template expressions using git repo state.
 	if project, err = ProcessImageTemplates(project); err != nil {
 		return nil, err