Reduce repetition and improve structure of i18n locales files

[johncowen]

Description

It should be really easy to figure out where to go to change the text via the i18n files. Being easy probably means being able to look at the URL of the page you are on and from that it being obvious which file and nested property corresponds to the text you are looking at.

As URLs/Routes are nested this possibly means a more nested structure that follows the URL.

But ideally we also want to reduce repetition, so just because we have a button that says Create in several nested URLs/Routes we should have several nested places in the locales files where we define the text Create.

There's probably more to say here but we should probably save those details/ideas until we come to do discuss this in more depth.

Vaguely related:

• https://github.com/kumahq/kuma-gui/issues/2430
• https://github.com/kumahq/kuma-gui/issues/2429