Add HTTP2 support

[sacOO7]

• Add HTTP2 support as per https://www.siakabaro.com/use-http-2-with-httpclient-in-net-6-0/
• Extension to https://github.com/ably/ably-dotnet/issues/1174
• This is required as per supported features matrix -> https://sdk.ably.com/builds/ably/ably-dotnet/main/features/ ( check at the bottom )

┆Issue is synchronized with this Jira Task by Unito

[sync-by-unito[bot]]

➤ Automation for Jira commented:

The link to the corresponding Jira issue is https://ably.atlassian.net/browse/SDK-4118