Added German translation and hassfest validator for custom integrations

[jwiesel]

Just a minor one:

• Adding a German translation
• Minor updates in strings
• Included the hassfest validator for custom HomeAssistant components.

[jay-oswald]

Thanks @jwiesel I hadn't seen that hassfest validator before looks great. Just the conflicts from the other PR's already being merged.

Also If you can update both en and ge granslations about the IP address, WiCAN supports mDNS now, and thats the method we should be encourging people to use, removes the need for a static IP

[jay-oswald]

@jwiesel also just invited you as collabirator, you've done just as bout as much as I have for this now, and will be able to list you as codeowner for getman translation for future changes to it and if your interested to help review for other PR's by others in the future

[jay-oswald]

@jwiesel just put in the hassfest validator directly now, was keen to get that running and see how it worked before the german translation was updated

[jwiesel]

Hi @jay-oswald ,
thanks for the invitation. I just accepted. Happy to contribute! :-)

Regarding mDNS: I tested connecting to WiCAN using the mDNS-name, but ran into issues.
There are also some discussions around it:

1. in context of HomeAssistant: Cannot specify powerview-g3.local as the hub address during setup home-assistant/core#134364
2. in context of aiohttp: aiodns does not work with mDNS and is the default resolver aio-libs/aiohttp#10186

Therefore I'd leave the mDNS part out of this translation PR for now. When we get mDNS to work, we can update the translations as well.