feat: migrate the `codePlugin` from `@vuepress/markdown` to `plugin-shiki` and `plugin-prismjs`

[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

see https://github.com/vuepress/core/issues/1550

Screenshots

Before

After

[coveralls]

Pull Request Test Coverage Report for Build 9156129729

Details

• 296 of 306 (96.73%) changed or added relevant lines in 20 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+7.3%) to 57.056%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
plugins/plugin-prismjs/src/node/parser/notation.ts	32	33	96.97%
plugins/plugin-shiki/src/node/resolveHighlight.ts	26	28	92.86%
plugins/plugin-prismjs/src/node/parser/getCodeParser.ts	42	45	93.33%
plugins/plugin-prismjs/src/node/prismjsPlugin.ts	0	4	0.0%
<!--	Total:	296	306	96.73%	-->

Totals
Change from base Build 9123655949:	7.3%
Covered Lines:	993
Relevant Lines:	1567

---

💛 - Coveralls

[Mister-Hope]

Also check #135

[pengzhanbo]

Also check #135

It appears that the current shikiSetup() has already implemented the same functionality.

[meteorlxy]

Same here. UT or E2E is required

[pengzhanbo]

Same here. UT or E2E is required

Added test cases identical to the codePlugin in @vuepress/core.

[pengzhanbo]

@meteorlxy @Mister-Hope Cc, this PR is ready.