Feature/fos 55/events styling

[markconroy]

Adds some layout tweaks to events listing page, so it now looks like this:

[Polynya]

Please make the theme changes in ecc_theme

[markconroy]

Please make the theme changes in ecc_theme

I don't want to put any changes for the theme into ecc_theme until that theme has gotten to live.

[markconroy]

Marking as blocked until shared theme gets to main

[markconroy]

I've added "Add to calendar" functionality, so marking this as draft until we get that tested.

[markconroy]

Thanks @Polynya, I've made those changes now.

[Polynya]

Thanks @markconroy. Can we keep your 4 PRs open for now, until we know what is going to be deployed to Prod first, Fostering or Theme Sharing.

[Polynya]

@markconroy the shared theme has finally be deployed to Prod. The Essex theme is no longer used and will be deleted from this repo (LP-59). Please move the styling from this PR to https://github.com/essexcountycouncil/ecc_theme

If the styles are unique to Gov then put them in ecc_theme_gov but if they could be used by Intranet in the future then they should go in ecc_theme, the shared base theme.