Nvim: restructure all plugins configuration

.config/nvim/after/available/ultisnips.rc.vim

@@ -0,0 +1,8 @@
+" Set completeopt to have a better completion experience
+"set completeopt=menuone,noinsert,noselect
+let g:completion_enable_snippet = 'UltiSnips'
+"iunmap <Tab>
+"map <c-s> <C-R>=UltiSnips#ExpandSnippet()<CR>
+"let g:UltiSnipsExpandTrigger="<c-s>"
+let g:UltiSnipsJumpForwardTrigger="<tab>"
+let g:UltiSnipsJumpBackwardTrigger="<S-tab>"