Excluding current-directory MRU files from general 'files' MRU, when displayed

Nobody has claimed this yet.

So, at the moment, after some configuration ... my Startify looks like this:

```
[e]

Recent files (/Users/ec/Sync/Code/FSharpMod):

[a]  FSharpMod.sln
[d]  Source/FSharpModLibrary/FSharpModLibrary.fsproj
[f]  Source/CSharpModLibrary/CSharpModLibrary.csproj
[h]  Source/CSharpModLibrary/Helloicate.cs
[l]  Makefile
[w]  Source/FSharpModLibrary/Library1.fs
[r]  Source/CSharpModLibrary/Properties/AssemblyInfo.cs

Recent files elsewhere:

[y]  ~/Sync/Code/HelloCSharp/HelloCSharpSolution.sln
[o]  ~/Sync/Code/FSharpMod/FSharpMod.sln
[p]  ~/Sync/Code/FSharpMod/Source/FSharpModLibrary/FSharpModLibrary.fsproj
[z]  ~/Sync/Code/FSharpMod/Source/CSharpModLibrary/CSharpModLibrary.csproj
[x]  ~/.local/share/nvim/plugged/vim-startify/autoload/startify.vim
[c]  $SYSTEM_REPO/Dotfiles/vim/lua/lsp-settings.lua
[n]  ~/Sync/Code/FSharpMod/Source/CSharpModLibrary/Helloicate.cs
[m]  ~/.cache/nvim/lsp.log
[,]  ~/Sync/Code/FSharpMod/Makefile
[A]  $SYSTEM_REPO/Dotfiles/vimrc

...
```

I'd really like to exclude items that show up in the first list, from *also* showing up in the second list. Is there any way to do this?

No source file or test is named. Begin at Startify's configuration and the MRU display entry point, reproduce the two lists shown, and verify that entries in "Recent files" are absent from "Recent files elsewhere".

Written by the indexing model from the issue text.