Move lsp config to local file structure

.config/nvim/lsp/ballerina.lua

@@ -0,0 +1,13 @@
+---@brief
+---
+--- Ballerina language server
+---
+--- The Ballerina language's CLI tool comes with its own language server implementation.
+--- The `bal` command line tool must be installed and available in your system's PATH.
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'bal', 'start-language-server' },
+  filetypes = { 'ballerina' },
+  root_markers = { 'Ballerina.toml' },
+}