Enable Syntax Highlight and automatic formatting of JSON and XML

[micsco]

Adds support for syntax highlighting of XML and JSON files (#5)

• Just JS/JSON and XML support enabled for now (to optimise JS size)
• Does a shallow copy of the currentRequest (so that when changes are made the original is not overriden)
• Enable formatting in the setCurrentRequest method
• Adds XML pretty printing/formatting as well

Fixes #5
Fixes #60

[micsco]

@fredsted This works as I test it:
XML:

JSON:

[micsco]

Another JSON example with more types to show highlighting:

[micsco]

@fredsted Are you happy with this as default style? Not sure what you wanted to use here; being able to choose would be great but added a level of complexity (plus additional preference to have somewhere)

I personally prefer a dark style

[micsco]

Added XML formatting too:

[fredsted]

Looks awesome! Great work. I think a lot of users will be happy about the XML formatting.

Regarding the theme, I'd like to keep it a bright theme so it fits with the rest of the app. I think an app-wide dark mode toggle would be nice.

[micsco]

Awesome, I haven't had a chance to test the limits of the formatters, but if you're happy with it go ahead and merge 👍

[fredsted]

Gave it a spin, and the only minor thing is that the formatting can't be toggled on/off immediately on the checkbox - if I want to see how the request looks unformatted, I have to turn formatting off and click back to another request. For me that's useful when you want to see exactly what's returned from the webhook.

I might try to fix this myself, but going to merge this for now.

Thanks again!