The idea is that all configuration will be managed in a centralised
location. The `WorkspaceConfiguration` component will be attached to the
main language server will be responsible from merging configuration
values from a number of sources.

- Initialization options
- ``workspace/configuration`` requests
- Configuration files

While this is not implemented yet, this component will also make sure
that the configuration values are kept up to date. Eventually features
will be able to subscribe to changes in the sections that they are
interested in.

Upon receiving the `initialized` notification the server dynamically
registers to receive `workspace/didChangeConfiguration` notifications,
if the client supports it.

The server will also early request the entire `esbonio` configuration
section for each workspace root and the global config so that it's ready
to serve internal configuration requests from features.

This commit also updates the old uses of `server.get_user_config` to use
the new `server.configuration.get` API

Rather than have the logging setup be anything "special", it is now just
another LanguageFeature allowing it to take advantage of the APIs
provided to them.

To align with the changes in how the server asks for configuration
values, this updates and simplifies the code that injects the user's
configured Python environment into returned configuration.

`lsp-devtools` is too heavy a dependency to bundle for it to be worth
it, especially when you consider the proportion of users who are
actually going to make use of it.

Instead, the extension now assumes that it is available on the user's
PATH

Since the language server treats `workspace/configuration` requests as
an override for any options set via config file, it's now important to
only send the options that the user has actually set.

This means most config options in the VSCode extension are now `null` by
default.

Options are read from the `tool.esbonio` namespace

For clients that support it, the language server will be able to listen
for changes to `pyproject.toml` files and update its configuration
accordingly.

- Move to reference section
- Add a custom domain to document esbonio
- Explain the updated configuration behavior