Add method to script editor websocket that lists scripts available for subscription

[WolfGangS]

Description

Adds a method for the web socket server to allow 3rd party tools to query scripts available for subscription. Useful for the sl-vscode-plugin to be able to resubscribe after a connection loss (like the user updated vscode, or similar)

Also useful for plans to add support for a cli version of the plugin, to allow broader editor compatibility.

Related Issues

Issue Link: relates to secondlife/sl-vscode-plugin#43

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Checklist

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Additional Notes

Discussed with @Rider-Linden before, so likely more his wheelhouse for review.

I suspect there may be some issue I am missing with my changes to LLScriptEditorWSServer::unsubscribeConnection but they (or something like them) are needed else a websocket connection closing flushes scripts from the subscription list, even though they are still open in viewer, and on disk in the temp directory.

[marchcat]

Thank you!

[marchcat]

Mac build complains about unused connection_id here.

error: lambda capture 'connection_id' is not used [-Werror,-Wunused-lambda-capture]
290 | [that, connection_id](const std::string&, const LLSD&, const LLSD& params) -> LLSD

Suggested change

	[that, connection_id](const std::string&, const LLSD&, const LLSD& params) -> LLSD
	[that](const std::string&, const LLSD&, const LLSD& params) -> LLSD

[Rider-Linden]

Just Marchcat's change and the script unsubscribe list thing.

[Rider-Linden]

This is going to leave the dead subscription record in the map....

[WolfGangS]

mSubscriptions is a map of scripts open in sl available to subscribe to, as they don't have a connection set until a websocket connetion subscribes.

Scripts are added when a user presses edit on the in viewer script editor. If they are removed from mSubscriptions when a websocket unsubscribes, then the user has to press edit in sl again to be able to resubscribe to the script.

For external tools to be able to reconnect, the script must still exist in the subscriptions list to subscribe to them.

So this change makes socket unsubscribe only do the inverse of what subscribing does in handleScriptSubscribe,

So the behavior is

• Add entry to mSubscritpions - Press Edit on in viewer script editor window - subscribeScriptEditor
• Remove entry from mSubscriptions - Close in viewer script editor window - unsubscribeEditor
• Set mSubscription connection - Web socket connects and subscribes to script - handleScriptSubscribe
• Unset mSubscription connection - Web socket unsubscribes or closes. - unsubscribeConnection

If that's not desirable, then this might need a larger rework, to achieve resubscribing.