Addresses issues with Pollen.com API troubles

[bachya]

Description:

Addresses a recently revealed 500 error within the Pollen.com API. In short:

1. As long as crucial data is returned from the API, sensors are created; non-crucial data is merely ignored (whereas previously, the sensor would fail to show).
2. Any API issues are properly caught and logged (currently logged under DEBUG – found that any other level spammed the logs way too much without a way to address).

Related issue (if applicable): fixes #12916

Pull request in home-assistant.github.io with documentation (if applicable): N/A

Example entry for configuration.yaml (if applicable):

sensor:
- platform: pollen
  zip_code: "00544"
  monitored_conditions:
    - allergy_average_forecasted
    - allergy_average_historical
    - allergy_index_today
    - allergy_index_tomorrow
    - allergy_index_yesterday
    - disease_average_forecasted

Checklist:

• The code change is tested and works locally.

If the code communicates with devices, web services, or third-party tools:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass

[balloob]

For another PR: Would it make sense to validate this as just str ? That way it will enforce people to put quotes around their zip code in their config.

[bachya]

Ah, that's a great idea! I'll open it up.

[balloob]

🐬