Fix excessive rerendering of history charts

[larena1]

Breaking change

Proposed change

Closes #8274

When @spacegaier reimplemented the history chart as LitElement, that unfortunately broke their tooltips because the chart would rerender on every change of the hass object. In my case that was every 500 ms and I'm not able to read that fast.

This PR implements shouldUpdate so the chart only rerenders when there was either a change to its own entity or the underlying history data.

Type of change

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

Example configuration

Additional information

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

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[homeassistant]

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