replace csharp_ls with omnisharp

lua/custom/plugins/csharpls-extended-lsp.lua

@@ -1 +0,0 @@
-return { 'Decodetalkers/csharpls-extended-lsp.nvim' }

lua/custom/plugins/omnisharp-vim.lua

@@ -0,0 +1 @@
+return { 'OmniSharp/omnisharp-vim' }

lua/plugins.lua

@@ -174,7 +174,7 @@ require('lazy').setup({
               run_on = 'type', -- or `save`
             },
           },
-          csharp_ls = {},
+          omnisharp = {},
           netcoredbg = {},
           clangd = {
             cmd = { 'clangd', '--background-index', '--clang-tidy' },