feat(plugin-comment): support more Giscus built-in themes

[SuniRein]

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• Read the Contributing Guidelines.
• 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
• New feature
• Other

Description

Providing more Giscus built-in themes.

Screenshots

Before

After

[Mister-Hope]

Btw, can you check locales as well? If there are new locale support added, it would be great to add them as well.

[SuniRein]

Sure. See #352

[coveralls]

Pull Request Test Coverage Report for Build 13268375905

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall first build on main at 59.656%

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Totals
Change from base Build 13259810273:	59.7%
Covered Lines:	1349
Relevant Lines:	2044

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💛 - Coveralls