feat: [SKU modularization] sku handler interface (#357)

**Reason for Change**:
Adding a CloudSKUHandler interface that will be used to modularize gpu
skus across multiple cloud platforms

**Requirements**

- [ ] added unit tests and e2e tests (if applicable).

**Issue Fixed**:
<!-- If this PR fixes GitHub issue 4321, add "Fixes #4321" to the next
line. -->

**Notes for Reviewers**:
The cloud specific implementations and fixes/updates to current code
will be part of future PRs.

pkg/sku/cloud_sku_handler.go

@@ -0,0 +1,16 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+package sku
+
+type CloudSKUHandler interface {
+	GetSupportedSKUs() []string
+	GetGPUConfigs() map[string]GPUConfig
+}
+
+type GPUConfig struct {
+	SKU      string
+	GPUCount int
+	GPUMem   int
+	GPUModel string
+}