This fixes#1005.
Defaults to `ask` which prompts users each time whether to start `cargo watch`
or not. `enabled` always starts `cargo watch` and `disabled` does not.
This allows users to control whether or not they want to see the "workspace
loaded" notification.
This is done on the server side using InitializationOptions which are provided
by the client. By default show_workspace_loaded is true, meaning the
notification is sent.
This further fixes problems when having a VIM extension (at least vscodevim)
enabled, by not calling `overrideCommand('type', commands.onEnter.handle)` when
enableEnhancedTyping is set to `false`.
The problem is dependent on the order in which extensions are activated, if
rust-analyzer is activated before `vscodevim`, rust-analyzer will register the
`type` command, and when `vscodevim` finally attempts to activate, it will fail
to register the command. This causes `vscodevim` to stop working properly.
This setting allows users to disable the registerCommand `type` in
rust-analyzer, allowing `vscodevim` to work. The setting defaults to `true`.
Currently changing the setting requires reloading of the window.
