feat: refactor the HTML to use html/template and to inject styling for other IDEs [IDE-326]

[teodora-sandu]

Description

This PR refactors the HTML template used for the OSS Sugestion Panel so that it's more secure and uses the html/template library. This also refactors the template so that it injects icons directly in LS and so other IDEs don't need to know what icons to inject. It adds a ${ideStyle} variable so that in both VSCode and IntelliJ we can inject the IDE specific styling, like we do for Snyk Code.

To test this, need to use snyk/vscode-extension#482.

Checklist

• Tests added and all succeed
• Linted
• README.md updated, if user-facing
• License file updated, if new 3rd-party dependency is introduced

🚨After having merged, please update the CLI go.mod to pull in latest language server.

[bastiandoetsch]

Wondering, if caching/memory will become an issue with 1000s of issues if we embed the svg like that. Do you know how Chrome handles this?

[teodora-sandu]

Do you mean we might run into trouble ebecause we would be using a lot of memory if we cache the same SVG multiple times?

[cat2608]

I've been thinking about this and at the very beginning of this migration, when we were just supporting IntelliJ and writing the HTML and CSS from scratch, we embedded everything in one single HTML file, trading DRY for velocity.

Now that the project has grown and VSCode and IntelliJ are loading CSS rules anyway, I think we could start considering removing the CSS and SVGs from the Language Server and moving them to the IDEs as separate assets.

Benefits:

1. Reduced Redundancy: Each vulnerability doesn't need to embed the same CSS and SVGs.
2. Improved Performance: Smaller HTML payloads and better caching of static assets.

WDYT @teodora-sandu @bastiandoetsch

[bastiandoetsch]

As we're at it - should we just update it to CVSSv4? ;)

[teodora-sandu]

Done! But I didn't change it in the LS message type, since that would affect our IDEs being able to read this value

[teodora-sandu]

snyk/vscode-extension#482 should be merged first before this.

[cat2608]

Maybe we can remove the else?

func getExploitMaturity(issue snyk.OssIssueData) string {
	if len(issue.Exploit) > 0 {
		return issue.Exploit
	}
	return ""
}