Refactor config and state

[jakobrosenberg]

This PR organizes state and configs better than the old state manager.

• It gets rid of state and config mutation
• Each config or state entry now has its own store. These can be extended if needed
• There's now a clear distinction between what data lives in VSCode config, VSCode state and a Pymakr session
• Devices each have an entry in the config object at pymakr>devices>configs

The old pymakr>devices>config should probably be removed. This feature has never made it into stable, so I think it's okay rename or remove it. The old pymakr.config store should probably be deprecated

For new config / state API, please see: https://github.com/pycom/pymakr-vsc/compare/next-staging...refactor-config-and-state?expand=1#diff-e7ad3aaa4e75faf6a5567941fbf5d70863b7d9ef94e4d6aa72b63d2a63dbb4cb

[jakobrosenberg]

:tada: This PR is included in version 2.16.0 :tada:

The release is available on:

• Visual Studio Marketplace
• GitHub release

Your semantic-release bot :package::rocket: