Remove extension default snippets

[hyangah]

Gopls is enabled by default, and it can provide context-aware, better suggestions than snippets.
Snippets are often too opinionated, and interfere with the suggestions from the language server.
VS Code supports user snippets so users can organize the snippets to their liking.

I heard the news that the recently released python extension finally removed the default snippets.
https://github.com/microsoft/vscode-python/blob/release-2021.01/CHANGELOG.md#enhancements

Related: #160

What do you think?

[marwan-at-work]

There are two snippets I use all the time: pkgm and iferr

I know gopls has a really nice if err != nil snippet completion, but that one is only triggered on specific conditions, so as a fallback I tend to use the default iferr snippet completion frequently.

I also use tys and tyi as well.

Of course, if vscode-go removed those snippets I can just add them myself as "Custom User Snippets", so I'm happy either way.

Maybe it's worth reducing the snippets or moving them to gopls?