fetch current container runtime config through the command line

Signed-off-by: Tariq Ibrahim <tibrahim@nvidia.com>

add default runtime binary path to runtimes field of toolkit config toml

Signed-off-by: Tariq Ibrahim <tibrahim@nvidia.com>

[no-relnote] Get low-level runtimes consistently

We ensure that we use the same low-level runtimes regardless
of the runtime engine being configured. This ensures consistent
behaviour.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Co-authored-by: Evan Lezar <elezar@nvidia.com>

address review comment

Signed-off-by: Tariq Ibrahim <tibrahim@nvidia.com>

pkg/config/toml/source-cli.go

@@ -0,0 +1,45 @@
+/**
+# Copyright 2024 NVIDIA CORPORATION
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package toml
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+)
+
+type tomlCliSource struct {
+	command string
+	args    []string
+}
+
+func (c tomlCliSource) Load() (*Tree, error) {
+	//nolint:gosec  // Subprocess launched with a potential tainted input or cmd arguments
+	cmd := exec.Command(c.command, c.args...)
+
+	var outb bytes.Buffer
+	var errb bytes.Buffer
+
+	cmd.Stdout = &outb
+	cmd.Stderr = &errb
+	if err := cmd.Run(); err != nil {
+		// TODO: Log to stderr in case of failure
+		return nil, fmt.Errorf("failed to run command %v %v: %w", c.command, c.args, err)
+	}
+
+	return LoadBytes(outb.Bytes())
+}