Change activation event to `workspaceContainers` about vscode-coverage-gutters

[ryanluker]

@SethFalco Thanks for the ticket!

Definitely would be better to turf the on startup instantiation of this extension (this was the only option when I initially developed it, I think...).

I like both ideas, but I think it is reasonable to only load the extension if an applicable file is found. I do wonder about how we might consider other file types not defined in the default list.

https://github.com/ryanluker/vscode-coverage-gutters/blob/master/package.json#L129-L135

[SethFalco]

I do wonder about how we might consider other file types

Unfortunately, I don't think VSC has a way to change activation based on settings, so if you're expecting users to specify additional files that are not info.lcov or **/*.xml, then the only option would be onStartupFinished I think. 🤔

Some other extensions have a similar issue, for example SonarSource/sonarlint-vscode, prettier/prettier-vscode, and microsoft/vscode-eslint could just specify to only activate on the list of officially supported languages, but users can also have plugins/projects/settings that define or target other languages, so even if it's not too often, they need to use onStartupFinished instead.

Fine with using onStartupFinished at least, though?

[ryanluker]

@SethFalco Agreed that onStartupFinished sounds like a good first step!
Thanks for the links to over extensions as well, it looks to be the norm to use this event instead which is nice to keep inline with the community 👍🏻.

[ryanluker]

@SethFalco Thanks again for the contribution and the PR, the change should go out in 2.11.0