feat(plugin-shiki): move `<pre>` `style` attr to `preWrapper`

[pengzhanbo]

Before submitting the PR, please make sure you do the following

• [x] Read the Contributing Guidelines.
• [x] Provide a description in this PR that addresses what the PR is solving. If this PR is going to solve an existing issue, please reference the issue (e.g. close #123).

What is the purpose of this pull request?

• [ ] Bug fix
• [x] New feature
• [ ] Other

Description

• only move style
• delete tabindex

- <div class="language-*">
-   <pre class="shiki nord vp-code" style="background-color:#2e3440ff;color:#d8dee9ff">

+ <div class="language-*" style="background-color:#2e3440ff;color:#d8dee9ff">
+   <pre class="shiki nord vp-code">

[coveralls]

Pull Request Test Coverage Report for Build 9280274453

Details

• 8 of 8 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 56.5%

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Totals
Change from base Build 9280272439:	0.03%
Covered Lines:	996
Relevant Lines:	1576

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💛 - Coveralls