Add on_server_notification_async API

[predragnikolic]

closes #2494

This API allows LSP-* to hook into when a notification is received form the language server.

[predragnikolic]

... "The notification object."

I couldn't think of better 🙈

[TerminalFi]

Although Copilot is doing some unconventional ideas. The use case is strong, in that helpers could also us it to raise information

[predragnikolic]

Copilot is adhering to the spec here

https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#progress

The base protocol offers also support to report progress in a generic fashion. This mechanism can be used to report any kind of progress including work done progress (usually used to report progress in the user interface using a progress bar) and partial result progress to support streaming of results.

interface [ProgressParams](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#progress)<T> {
	/**
	 * The progress token provided by the client or server.
	 */
	token: [ProgressToken](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#progress);

	/**
	 * The progress data.
	 */
	value: T;
}

[predragnikolic]

Just for leaving a clue on how to implement it in packages:

Here example with NpmClientHandler

from lsp_utils import NpmClientHandler

class LspMyPackage(NpmClientHandler):

    def on_server_notification_async(self, notification) -> None:
        if notification.method == '$/progress':
            print('read this notification', notification.params)

Here example with AbstractPlugin

from LSP.plugin import AbstractPlugin

class LspMyPackage(AbstractPlugin):

    def on_server_notification_async(self, notification) -> None:
        if notification.method == '$/progress':
            print('read this notification', notification.params)