gitignore: Ignore editor specific config files
Ignore VSCode specific config files. Probably people might want to add more other editor/IDE specific files to gitignore as of this commit though, we can prune it based on agreement later.
Note that VSCode seems to be the most widely used mordern editor (https://insights.stackoverflow.com/survey/2021#most-popular-technologies-new-collab-tools) and chromium is doing this as well https://github.com/chromium/chromium/blob/master/.gitignore#L70-L72
Motivated by !1250