UI enhancements

[gabriel-indik]

What would you like to be added?

• In Indexer, submissions and registry views: add skeleton loaders
• Ensure eslint plug-in for useQuery is enabled
• Add utility for displaying components based on theme (light/dark), example:

export const getThemedComponent = (lightComponent, darkComponent, theme) => {
   return theme === 'light' ? lightComponent : darkComponent
}

Why is this needed?

During the review process of #411 a number of suggestions were raised. It would be good to turn these suggestions into enhancements.