Add struct to allow universal method of setting jvm parameters

issue 中没有指定文件、测试或入口点。首先定位 operator framework 的公共配置类型，然后将 HashMap、Vec 和自定义结构体选项与所述的合并要求进行比较。完成的标准是发布一个可复用的 JVM 参数结构，并确定其表示方式和合并行为。

A customer wanted to override the jvm heap settings for the Druid operator today and was unable to do this.
In this specific instance it was resolved by the addition of resource configs to the Druid operator, which barely missed the last release window and hence is only available in the nightly version at the moment.

In the future it may become necessary though to allow users to override jvm parameter in some operators and ideally we'll want to do this in a universal way.

We should publish a struct in the operator framework that can be used by operators to allow setting these settings.

We have considered multiple versions of this:

1. A HashMap<String, String>
2. A Vec
3. A custom struct with both a HashMap and a List to accomodate both

All of these have drawbacks and benefits, especiallly when considering how to merge these.
At the moment we tend towards option 2 as this is the most simple one.

The downside is, that is doesn't allow merging with higher level structs to for example override the value of -Xmaxmx=100 with -Xmaxmx=200 for a rolegroup, as this is only a string to us and we won't understand that it refers to the same setting.

We do think that this is an acceptable compromise, since hopefully the need to override values here should not be too frequent.