Implement Wind Gust speed in Weather entity component

[gjohansson-ST]

Proposed change

As per decision in home-assistant/architecture#778 this implement wind_gust_speed in attributes and forecast attribute in Weather entity component

Does not implement it's own unit or conversion but uses same as for wind_speed

Developer PR: home-assistant/developers.home-assistant#1811

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
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• Tests have been added to verify that the new code works.

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (weather) you are listed as a code owner for? Thanks!

Code owner commands

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