This PR overhauls extension registration in order to make it more
modular.
The `extension` crate now contains an `ExtensionHostProxy` that can be
used to register various proxies that the extension host can use to
interact with the rest of the system.
There are now a number of different proxy traits representing the
various pieces of functionality that can be provided by an extension.
The respective crates that provide this functionality can implement
their corresponding proxy trait in order to register a proxy that the
extension host will use to register the bits of functionality provided
by the extension.
Release Notes:
- N/A
This PR updates the `ExtensionLspAdapter` to go through the `Extension`
trait for interacting with extensions rather than going through the
`WasmHost` directly.
Release Notes:
- N/A
This PR extracts the `ExtensionIndexedDocsProvider` implementation to
the `indexed_docs` crate.
To achieve this, we introduce a new `Extension` trait that provides an
abstracted interface for calling an extension. This trait resides in the
`extension` crate, which has minimal dependencies and can be depended on
by other crates, like `indexed_docs`.
We're then able to implement the `ExtensionIndexedDocsProvider` without
having any knowledge of the Wasm-specific internals of the extension
system.
Release Notes:
- N/A
