fix(plugin): allow duplicate parameter names across different locations

[Spritualkb]

Description

This PR fixes the plugin parameter validation logic to allow duplicate
parameter names across different locations while maintaining uniqueness within
the same location.

Changes:

• Update frontend checkSameName function to validate uniqueness only within
  same location
• Modify backend parameter validation to use location-name as unique keys
• Enable same parameter names in different locations (Header/Body/Query/Path)
• Fix 参数名称不能重复 error when parameters share names across locations

What type of PR is this?

fix: A bug fix

Check the PR title.

• This PR title match the format: <type>(optional scope):
  <description>
• The description of this PR title is user-oriented and clear enough for
  others to understand.
• Add documentation if the current PR requires user awareness at the usage
  level.

(Optional) Translate the PR title into Chinese.

fix(plugin): 允许不同位置的参数名称重复

(Optional) More detailed description for this PR(en: English/zh:

Chinese).

en:
Previously, the plugin configuration system prevented users from using the
same parameter name in different locations (e.g., having a "token" parameter
in both request headers and request body). This was overly restrictive and
blocked legitimate use cases.

This PR implements a "location + name" combined validation approach:

• Frontend: Modified checkSameName function to include location filtering
  (dataItem.name === val && dataItem.location === item.location)
• Backend: Updated parameter validation to use "location-name" as unique keys
  instead of just parameter names
• Users can now have parameters with the same name in different locations
  (Header, Body, Query, Path)
• Validation still prevents true duplicates within the same location

zh(optional):
之前的插件配置系统阻止用户在不同位置使用相同的参数名称（例如在请求头和请求体中
都有"token"参数），这种限制过于严格，阻碍了合理的使用场景。

此PR实现了"位置+名称"联合验证方法：

• 前端：修改 checkSameName 函数，增加位置过滤（dataItem.name === val && dataItem.location === item.location）
• 后端：更新参数验证逻辑，使用"位置-名称"作为唯一键而不是仅使用参数名称
• 用户现在可以在不同位置（Header、Body、Query、Path）使用相同的参数名称
• 验证逻辑仍会阻止同一位置内的真正重复

(Optional) Which issue(s) this PR fixes:

Fixes the "参数名称不能重复" (parameter names cannot be duplicated) error that
incorrectly triggered when users had legitimate use cases requiring the same
parameter name in different request locations.

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[Spritualkb]

这个线上的扣子空间都有这个限制可以的话线上的也修复一下，我今天想新建一个插件发布啥的都遇到这个bug

[fanlv]

cc @mrh997 看看。