feat: add syntax highlighting for JSON payload in web version

[nktnet1]

PR Checklist

What is the current behavior?

No syntax highlighting for JSON payload in the web version of MQTTX.

Issue Number

Related to #1362, #1381 and #1390, but for Web.

What is the new behavior?

JSON payload now has syntax highlighting.

Light Theme:

Dark Theme:

Night Theme:

Does this PR introduce a breaking change?

• Yes
• No

Specific Instructions

Are there any specific instructions or things that should be known prior to review?

1. The theme I use are:

   1. Light: https://github.com/highlightjs/highlight.js/blob/main/src/styles/default.css
   2. Dark: https://github.com/highlightjs/highlight.js/blob/main/src/styles/dark.css
   3. Night: https://github.com/highlightjs/highlight.js/blob/main/src/styles/night-owl.css

   Also, only the JSON language was registered.

2. With highlight.js, I had to use highlight.js@v10.7.3 (instead of 11.x.x) and @highlightjs/vue-plugin@1.0.2 (instead of 2.x.x) for compatibility with Vue 2.

   There were also typescript issues that required ./src/types/highlight.d.ts to be included, where type any was used. Haven't figured out why or how else to work around this.