feat(i18n): allow setting i18n namespaces via an environment variable

[aptmac]

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Fixes: #1526

Description of the change:

This change allows the i18n namespace(s) to be set as an environment variable.

To do so, I've added useCryostatTranslation to @i18n/i18nextUtil which is just useTranslation with the required namespaces being set.

I've also moved i18nResources and i18nLanguages from @i18n/config to @i18n/i18nextUtil, because I was encountering issues where the Settings page was breaking on the Console plugin side and using a different i18n object than what the Console was expecting.

I have a branch for the console plugin that includes some work to use these changes: aptmac/cryostat-openshift-console-plugin@c8d2d54

At the moment that branch is out of sync with upstream, I'll be fixing that up soon. That commit includes the ability to combine the cryostat-web common and public with the console plugin side common, and renames it to plugin__cryostat-plugin so it can be picked up by the Console.

Motivation for the change:

This change is helpful because it will allow the console plugin to pass it's i18n namespace (something like plugin__cryostat-plugin) and allow the cryostat-web pages to access the localized strings.

Before

(nothing changes for cryostat-web, but here's the console plugin):

After