Revamp react-tokens logic

Describe the enhancement or change
Our token generation in the react-tokens package needs to be reworked as the logic we use to determine css var values doesn't match 1:1 with how that value will be determined in browser, this can lead to build breaking bugs with recursively defined values.

We've implemented a temporary fix for this, but it is still not optimal as differences in behavior could occur if a var is defined multiple times in a stylesheet. Ideally we should only parse the css within the root selector of the stylesheet.

Additionally, core currently has to add some variables to the root scope for the sole purpose of having the token created in react-tokens, ideally this will not be required in the future.

Jira Issue: PF-92

首先定位 react-tokens 包及其临时的 token 生成修复，然后检查 core 如何向根作用域添加变量。将该包对 CSS 变量的解析与浏览器行为进行比较，尤其要关注递归定义或重复定义的变量。完成的标准是根作用域解析与浏览器解析一致，并且 core 不再需要仅用于创建 token 的额外变量。