feat(websocket-plugin): add WebSocketDisconnected, WebsocketMessageError actions

[kwalski]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngxs/store/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

• Dispatches WebSocketDisconnected action upon disconnect to allow user write a reducer/effect to track websocket connection state and retry if required. Note that this is plugin dispatched and hence different to DisconnectWebSocket which can be programatically dispatched
• WebsocketMessageError was not dispatched because this._socket in websocket-subject.ts is not handling error and complete functions in subscribe

Issue Number: N/A

What is the new behaviour?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

#820

[eranshmil]

I checked and there is a lot of inconsistency all over, not related to your PR.
The main issue is that the plugin's module and options are written with lower s. (ie NgxsWebsocketPluginModule)

If we want to deal with it, it should be fixed for the next major version.

@markwhitfeld @splincode @arturovt Any thoughts?

[arturovt]

@eranshmil my opinion is we have to release the next version as soon as we can, because there a lot of features awaited by people. What do you think?

[eranshmil]

@eranshmil my opinion is we have to release the next version as soon as we can, because there a lot of features awaited by people. What do you think?

We could merge this PR without the WebSocketMessageError, and release the minor version.
For the major version, all this inconsistency should be resolved.

[arturovt]

@eranshmil Yeah, probably, also could you please look with Mark at the edited markdown file, maybe there is some inconsistency in descriptions?

[markwhitfeld]

I agree, this PR is good to go other than the rename.
So the WebSocketMessageError should be named back to WebsocketMessageError.
It is tempting to make a concession but we need to follow semantic versioning.
In the next major release we will rename all occurences of Websocket to WebSocket to make it consistent

[kwalski]

So the WebSocketMessageError should be named back to WebsocketMessageError.

@markwhitfeld this is reverted

[splincode]

[markwhitfeld]

Fantastic! Thanks so much for this PR.