Configurable websocket exponential backoff

[adambor]

Motivation and Resolution

The WebSocketChannel is currently always using the exponential backoff, however some people might rather wanna opt-in to always use the same delay between retries (disable the exponential backoff). This is especially useful when you want the websocket connection to always keep retrying (e.g. when running it server-side).

RPC version (if applicable)

RPC 0.9 (websockets)

Usage related changes

• Users are able to disable exponential backoff for websocket connections, potentially allowing for infinite reconnection attempts with fixed retry delay, which is useful for long-lived server based applications.

Development related changes

N/A

Checklist:

• Performed a self-review of the code
• Rebased to the last commit of the target branch (or merged it into my branch)
• Linked the issues which this PR resolves
• Documented the changes in code (API docs will be generated automatically)
• Updated the tests
• All tests are passing

[tabaktoni]

Seems legitimate. @PhilippeR26

[tabaktoni]

lgtm