Remove discontinued crypto-js package

[lhw-1]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• Feature addition or enhancement
• Code maintenance
• DevOps
• Improve developer experience
• Others, please explain:

Partially addresses #2607.

Overview of changes:

As brought up with #2607, there are several npm vulnerabilities we could take a look at and potentially address.

This PR resolves the critical vulnerability caused by the crypto-js package in particular (mainly because it stands out as the only critical vulnerability).

Anything you'd like to highlight/discuss:

We started using the native crypto module in Node.js in #113, for the markdown-it radio buttons.

After PlantUML was introduced as a plugin, we started using crypto-js instead of the crypto module in #1403, which was a massive PR (and likely was overlooked). Since then, the crypto-js package was discontinued, and the npm package webpage even directly suggests using the native crypto module instead.

The vulnerability introduced by crypto-js is as seen here.

Given the use case for crypto-js in MarkBind was just for generating MD5 hashes in the PlantUML plugin (where security is not really a huge concern), it is not a critical issue on our end. Still, keeping the standard consistent and removing the scary critical keyword, in my opinion, is still a worthwhile improvement.

This PR simply removes the package and replaces the usage of crypto-js for MD5 hashes with that of the native crypto module.

Testing instructions:

Proposed commit message: (wrap lines at 72 characters)
Remove discontinued crypto-js package

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Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No unrelated changes

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Reviewer checklist:

Indicate the SEMVER impact of the PR:

• Major (when you make incompatible API changes)
• Minor (when you add functionality in a backward compatible manner)
• Patch (when you make backward compatible bug fixes)

At the end of the review, please label the PR with the appropriate label: r.Major, r.Minor, r.Patch.

Breaking change release note preparation (if applicable):

• To be included in the release note for any feature that is made obsolete/breaking

Give a brief explanation note about:

• what was the old feature that was made obsolete
• any replacement feature (if any), and
• how the author should modify his website to migrate from the old feature to the replacement feature (if possible).

[kaixin-hc]

good idea & lgtm, verified netlify deployment still works as expected. thanks!