Make actionEvent of extension more specific

[FieteO]

There is a warning in the package.json about the activationEvent: Using '*' activation is usually a bad idea as it impacts performance.

As explained in the vscode docs, the * corresponds to 'always activate'.
This PR makes this actionEvent more specific. Ideally, the extension should only be activated for json and yaml files using onLanguage:

"activationEvents": [
    "onLanguage:yaml",
    "onLanguage:json"
]

However the deleteYamlNode test case is failing then. Maybe it would make sense that someone with more experience of this project (@ak1394 ?) could take a look in a second step to improve this further

[ak1394]

Thanks for the PR! Unfortunately we can't quite get rid of activation on '*' at the moment. This extension contains two large chunks of functionality, one which is mostly self-contained and the other that requires user to configure credentials to access our cloud-based "42Crunch Platform".

At the moment we conditionally enable some of that functionality at the launch of the VS Code, if user has indeed configured platform credentials, therefore we have to activate as soon as possible.

We have plans to migrate away from using '*', but we are not quite ready to do it.

[FieteO]

Ah I see. Thanks for elaborating @ak1394 !

[ak1394]

Thanks for taking an interest in it!