Feature: 嵌套插件名称作用域优化

[yanyongyu]

Breaking

本 PR 更新了嵌套插件识别逻辑，根据插件的模块路径来判断是否为嵌套插件，例如：parent.plugins.sub_plugin 是 parent 的子插件。

另本 PR 更新了嵌套插件名称作用域，使得不同插件的子插件可以具有相同名称，例如：parent.plugins.sub_plugin 的 插件 ID 为 parent:sub_plugin。插件 ID 将以 : 分割作用域。

Breaking 影响的代码：（如果未使用嵌套插件则无任何影响）

• 现在使用 nonebot.get_plugin 时，应使用新版作用域 ID，即：nonebot.get_plugin("parent:sub_plugin")
• 现在使用 require 时，如果原先使用插件名称（非模块路径）调用，现在应使用新版作用域 ID，即 require("parent:sub_plugin")

Related

fix #2597
fix #2536

[codecov]

Codecov Report

Attention: Patch coverage is 96.84211% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 94.19%. Comparing base (e15d544) to head (bbf48af).

Files	Patch %	Lines
nonebot/plugin/__init__.py	90.62%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2665      +/-   ##
==========================================
- Coverage   94.21%   94.19%   -0.02%     
==========================================
  Files          48       48              
  Lines        4026     4050      +24     
==========================================
+ Hits         3793     3815      +22     
- Misses        233      235       +2     

Flag	Coverage Δ
unittests	94.19% <96.84%> (-0.02%)	⬇️

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[github-actions]

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