Moved econet from climate to water heater

[w1ll1am23]

Description:

This PR moves econet water heaters to the new water_heater component added with #17058

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#6676

Example entry for configuration.yaml (if applicable):

water_heater:
  - platform: econet
    username: test@test.com
    password: test1234

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

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

• Documentation added/updated in home-assistant.io

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

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

[MartinHjelmare]

Looks good!

[MartinHjelmare]

Please add a paragraph in the description that highlights the breaking change for the release notes.

[fabaff]

Breaking change:

The econet climate platform was moved to the new water heater implementation. Please update your configuration, use water_heater now.

[w1ll1am23]

@fabaff thanks I am on vacation so wouldn't be able to get to it for a few days.