Remove defunct CoinMarketCap integration

[frenck]

Breaking change

The CoinMarketCap integration has been removed. The API used by this integration has been out of service for a while not, breaking this integration.

Proposed change

This PR removes the CoinMarketCap integration. The API used by this integration was officially superseded by the new CoinMarketCap Professional API on December 4, 2018 and had been in a limited state to allow users to migrate before it was fully shut down on March 5, 2020.

References:

• https://pro.coinmarketcap.com/migrate/
• https://community.home-assistant.io/t/issue-32551coinmarketcap-platform-uses-an-outdated-api/176812
• Coinmarketcap integration broken/outdated. It uses new API now.  #32551
• Please remove coinmarketcap integration #46614
• Coinmarketcap Public API Deprecation #34297
• JSONDecodeError in coinmarketcap component. #26410
• CoinMarketCap API v1 will be decommissioned  #14437

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)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example entry for configuration.yaml:

# Example configuration.yaml

Additional information

• This PR fixes or closes issue: closes Coinmarketcap integration broken/outdated. It uses new API now.  #32551 closes Please remove coinmarketcap integration #46614
• This PR is related to issue:
• Link to documentation pull request: Remove defunct CoinMarketCap integration home-assistant.io#16609
• Link to pull request in the Brands repository: Remove defunct CoinMarketCap integration brands#2265

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been removed.

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

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

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

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.