Move common root marker list to plugin/lsp_settings.vim.
Update all uses to merge the two lists.
Test:
:edit lsp-settings/data/catalog.json
:Verbose ec lsp_settings#root_uri(extend(['catalog.json'], g:lsp_settings_root_markers))
file:///C:/david/settings/daveconfig/multi/vim/bundle/lsp-settings/data
:Verbose ec lsp_settings#root_uri(g:lsp_settings_root_markers)
file:///C:/david/settings/daveconfig
:Verbose ec lsp_settings#root_uri(extend(['rebar.config'], g:lsp_settings_root_markers))
file:///C:/david/settings/daveconfig
Install rls and edit a rust file.
