Change accelerator key for menu item: User Snippets from 'U' to 'S'

[stkb]

I often like to go into the user settings, which should be just a alt+f p u away. However both the "User Settings" and "User Snippets" menu items have the same accelerator key: U, which means having to press Enter as well.

So this commit changes the key or "User Snippets" from 'U' to 'S'. There's other instances of accelerator key duplication in the menus, but this one seemed easy to tackle.

[msftclas]

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[joaomoreno]

👍

[stkb]

Thanks!