[IS] Add climate sentences and tests

[Gussi]

Created climate domain sentences for Icelandic, and suitable tests for them.

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[Gussi]

As mentioned in #1255 Icelandic is an inflected language, due to this some tests are grammatically incorrect.

Hopefully we can solve this neatly, but that's out of scope for this PR.

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[frenck]

Because there hasn't been any activity on this PR for quite some time now, I've decided to close it for being stale.

Feel free to re-open this PR when you are ready to pick up work on it again 👍

../Frenck