Validate service offering name for ( Compute, System, Disk offerings)

### The required feature described as a wish

Currently cloudstack is allowing to create offering with the same name for Compute, System, Disk offerings

Where as Cloudstack validates name for (Backup , Network and VPC offerings )

for compute offerings we can have the same name

Expected behaviour

It would be great if Cloudstack can validate the service offering name for Compute, System, Disk offerings in order to maintain consistency across

首先定位现有的 Backup、Network 和 VPC offering 名称验证逻辑，然后追踪 Compute、System 和 Disk offering 的创建路径。比较这些行为，并为重复名称添加覆盖；完成的标准是这些 offering 类型能够按照描述一致地拒绝重复项。

由索引模型根据 Issue 内容生成。