Remove mermaid imports to resolve bundle size issue

[ruibaby]

This PR removes the import of the mermaid dependency and does not build it into the main.js file, as this causes the main.js file to become very large. Additionally, due to the current front-end plugin mechanism of Halo, we cannot use es module and dynamic import, resulting in an increasingly large bundle.js for plugins.

This PR changes the loading of mermaid resources in the editor to be consistent with the loading method used on the theme side.

Before:

After:

/kind improvement

Remove mermaid imports to resolve bundle size issue

[f2c-ci-robot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

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