feat(useWebSocket): allow undefined ref for url

[ferferga]

Description

I want to have a a global WebSocket in my app. Since the introduction of ref passing to useWebSocket, useWebSocket is much more useful for scenarios where you change between servers, since I can always expect the WebSocket to work and be up to date without any manual handling from our side. Everything works thanks to vue computed (to construct the webSocket url) and a ref to an object which contains the server URL.

However, expecting only URLs or strings makes it really difficult to have that webSocket always globally: there are situations in my app where no server is defined. Without this PR, I need to have a watcher and then instantiate the socket using useWebSocket. This PR solves all this logic.

Additional context

I also fixed the docs, which were with outdated types

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
  • feat(useWebSocket): redefine url / parameter #2200 is very similar in what this PR wants to aim. However, it's outdated, as it doesn't take into account that url can now be a ref, so my proposed solution for this make it much simpler for this kind of scenarios.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.