Change Container to Placeholder in live templates

[stevemessick]

Fixes #6288

Also updates a couple settings that got changed when I moved to IntelliJ 2022.2 as the dev platform.

@DanTup We can coordinate the actual date that this is released, if you want.

[DanTup]

@DanTup We can coordinate the actual date that this is released, if you want.

For most VS Code users this is coming from the server so will show up based on SDK version and probably not worth trying to sync.

I'll submit the SDK changes shortly, and do the same in the VS Code plugin for users on onlder SDKs that don't yet use server snippets. Thanks!

[DanTup]

By the way - the goal of this was to reduce triggering lints, but while testing my change I noticed that without const you can also trigger a lint:

So I think we should be using const Placeholder().

[stevemessick]

Good point. I thought people would immediately change Placeholder to something else. But really, a reference to that class is effectively a TODO and those can exist a long time.