How to use mouse selection to copy to system clipboard
**Is your feature request related to a problem? Please describe.**

Sorry I am not good at vim, with ubuntu native vim, mouse selection will be copied to system clipboad as default, but SpaceVim will not.

**Describe the solution you'd like**

Mouse selection will automatically be copied to system clipboard.

**Describe alternatives you've considered**

Edit with `vim file`, but copy with `cat <file>`.

**Additional context**

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