feat(comp:theme): supports prefix for token register

[sallerli1]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

用户需要自定义业务token时，不希望使用 --ix 前缀，而使用单独的前缀，但现在不支持

What is the new behavior?

支持自定义注册的token的变量前缀

Other information

[idux-bot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.19%. Comparing base (a50147b) to head (541a47c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1865   +/-   ##
=======================================
  Coverage   91.19%   91.19%           
=======================================
  Files         349      349           
  Lines       34269    34273    +4     
  Branches     2767     2767           
=======================================
+ Hits        31250    31254    +4     
  Misses       3019     3019           

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