Reduce weight of VersionConfiguration JSON

[RobQuincey-DC]

The VersionConfiguration JSON payload contains a lot of duplicated and unecessary data. The weight of this request could be reduced by being a bit smarter with what is actually returned and how. For example:

• Layer Source Types do not need the description included
• Bounds do not need the description included
• attributionHTML is probably not needed, and we could just have the renderedAttributionHTML
• params in WMS layers should be minified before being added (lots of wasted white space at the moment)

Slightly more work would be needed for these, but they would produce significant reductions

• Bounds within Layers are duplicated everywhere they are used. It should just be a reference
• Attributions within Layer Sources are duplicated everywhere they are used. It should just be a reference
• Layer Source Types within Layer Sources are duplicated everywhere they are used. It should just be a reference
• Layer source descriptions could be requested only when they are needed
• Info templates could be requested dynamically rather than included all at once