feat: support setting rendering templates for related posts on category

[guqing]

What type of PR is this?

/kind feature
/area core
/milestone 2.17.x

What this PR does / why we need it:

支持在分类上为关联的文章统一设置渲染模板

现在文章的模板生效顺序为：

1. 文章关联的分类上设置的文章模板，如果有多个则选择第一个
2. 文章上设置的自定义模板
3. 文章的默认模板

Which issue(s) this PR fixes:

Fixes #6101

Does this PR introduce a user-facing change?

支持在分类上为关联的文章统一设置渲染模板

[guqing]

Hi @ruibaby ,需要为分类增加文章模板的选择项,帮忙提供一下 UI

[codecov]

Codecov Report

Attention: Patch coverage is 61.53846% with 5 lines in your changes missing coverage. Please review.

Project coverage is 56.45%. Comparing base (5fdf6c0) to head (7d108d7).
Report is 239 commits behind head on main.

Files	Patch %	Lines
...o/app/theme/router/factories/PostRouteFactory.java	66.66%	3 Missing and 1 partial ⚠️
.../run/halo/app/core/extension/content/Category.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6106      +/-   ##
============================================
- Coverage     56.91%   56.45%   -0.47%     
- Complexity     3319     3551     +232     
============================================
  Files           587      625      +38     
  Lines         18968    20988    +2020     
  Branches       1401     1484      +83     
============================================
+ Hits          10795    11848    +1053     
- Misses         7594     8537     +943     
- Partials        579      603      +24     

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[ruibaby]

Hi @ruibaby ,需要为分类增加文章模板的选择项,帮忙提供一下 UI

Done

[JohnNiang]

/approve

[ruibaby]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang, ruibaby

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