[extractor/nhkradirulive] make station info non-fatal

[garret1317]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

R1 from Kanazawa is available as a temporary service due to the earthquake on the noto peninsula
https://www3.nhk.or.jp/netradio/kanazawa/
it only has the bare minimum to be playable - no station info, no nothing, just the stream url and the area name
it may be of interest to record, so this PR makes it so that the metadata download is non-fatal. everything past that is also non-fatal, so it all degrades reasonably gracefully

for an example do yt-dlp https://www.nhk.or.jp/radio/player/?ch=r1 --extractor-args nhkradirulive:area=kanazawa before/after this commit

Template

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check all of the following options that apply:

• I am the original author of this code and I am willing to release it under Unlicense
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What is the purpose of your pull request?

• Fix or improvement to an extractor (Make sure to add/update tests)
• New extractor (Piracy websites will not be accepted)
• Core bug fix/improvement
• New feature (It is strongly recommended to open an issue first)