Remove duplicate document.body.className effect

[lindapaiste]

Code cleanup 🧹
The components AccountView, CollectionView and DashboardView are all rendered inside of the App component. They do not need to set the document.body.className because this is already handled by the parent App.

Changes:
In all 3 components:

• removed lifecycle effect:

componentDidMount() {
    document.body.className = this.props.theme;
}

• removed theme from propTypes declaration
• removed theme from mapStateToProps

In AccountView only:

• converted to a function component to fix the ESLint error react/prefer-statelesss-function which popped up after deleting the componentDidMount function.
• used react-redux hooks instead of connect as a bunch of the properties in mapStateToProps were not actually used.

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123