[TS] Add support for negotiateVersion and connectionToken

[BrennanConroy]

Follow up to #13389 for the TS client

Couple things I changed from the other clients implementations that I'll fix for them in a different PR:

• negotiateVersion is not included after negotiation occurs
• negotiateVersion is not added multiple times when redirecting (otherwise this would break the service scenario)
• connectionToken is not stored anywhere

Side-note: Fixed a bug where the connectionId property wasn't updated when fallback occurs.

[xepozz]

@BrennanConroy I see that one of problems was:

connectionToken is not stored anywhere

So is it stored anywhere after this PR? Is it accessible?
I've researched almost whole library, but didn't find the way to access it. I think the way could be done with adding similar to

aspnetcore/src/SignalR/clients/ts/signalr/src/HubConnection.ts

Lines 126 to 128 in b5db4a9

	get connectionId(): string | null {
	return this.connection ? (this.connection.connectionId || null) : null;
	}

method, but I don't know anything about the library architecture.

[ghost]

Hi @xepozz. It looks like you just commented on a closed PR. The team will most probably miss it. If you'd like to bring something important up to their attention, consider filing a new issue and add enough details to build context.