fix: missing ServerWebExchange in plugin template processor extension

[guqing]

What type of PR is this?

/kind bug
/area core
/milestone 2.20.x

What this PR does / why we need it:

修复由 #6680 导致的插件模板处理扩展中无法获取到请求上下文的问题

#6680 修复了插件可以在模板处理扩展中通过请求上下文获取到 Halo 的 ApplicationContext 的问题
但这也引入了新的问题就是导致模板处理扩展无法获取到请求上下文，此 PR 通过判断传递给插件的 ITemplateContext 是否为 IWebContext，如果是则包装为 SecureTemplateWebContext 传递给插件，以解决此问题

Which issue(s) this PR fixes:

Fixes #6875

Does this PR introduce a user-facing change?

修复插件模板处理扩展中无法获取到请求上下文的问题

[sonarcloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

Attention: Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 57.03%. Comparing base (eff73dc) to head (17fb3c7).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
...lo/app/theme/dialect/SecureTemplateWebContext.java	50.00%	2 Missing and 1 partial ⚠️
...pp/theme/dialect/SecureTemplateContextWrapper.java	75.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6877      +/-   ##
============================================
+ Coverage     56.99%   57.03%   +0.04%     
- Complexity     3999     4008       +9     
============================================
  Files           714      716       +2     
  Lines         24110    24187      +77     
  Branches       1585     1594       +9     
============================================
+ Hits          13742    13796      +54     
- Misses         9756     9777      +21     
- Partials        612      614       +2     

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[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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