Remove unneeded files in lib/mermaid

[wtchangdm]

Some context: #980 (comment)

There was a finding that assets/lib/mermaid takes ~90MiB size. After digging the history a little, I am still curious why all files were included again:

1. It was only mermaid.min.js until 7740790.
2. Mermaid was removed from dependencies at 7e41c9c
3. Mermaid was re-introduced in 5a11829, with full folder copy command in package.json along with many other files

However, after checking the code that includes mermaid:

blowfish/layouts/partials/vendor.html

Lines 6 to 10 in c6c2689

	{{ if .Page.HasShortcode "mermaid" }}
	{{ $mermaidLib := resources.Get "lib/mermaid/mermaid.min.js" }}
	{{ $mermaidConfig := resources.Get "js/mermaid.js" }}
	{{ $mermaidConfig := $mermaidConfig | resources.Minify }}
	{{ $mermaidJS := slice $mermaidLib $mermaidConfig | resources.Concat "js/mermaid.bundle.js" | resources.Fingerprint "sha512" }}

Looks like what we need here is only mermaid.min.js.

Therefore I created this PR to remove the unneeded files and reduce the folder size from 90MiB to 3.3MiB.

This should benefit users using blowfish as hugo module and the ones who only shallow-clones the repo.

@nunocoracao please let me know if I missed anything.

Thanks!

[wtchangdm]

Oops, just found out I should fork from dev branch and send PR to it instead.

[wtchangdm]

The last two commits were caused by mistake as I was testing the result hugo module but changed the module name on wrong branch and have fixed it.