Make all plugin configs return a function

Simplifies writing the `config = ...` field for each plugin

lua/plugins/mason_lspconfig.lua

@@ -16,9 +16,13 @@
 
 -- https://github.com/williamboman/mason-lspconfig.nvim
 
-require("mason-lspconfig").setup({
-    -- A list of servers to automatically install if they're not already installed. Example: { "rust_analyzer@nightly", "lua_ls" }
-    -- This setting has no relation with the `automatic_installation` setting.
-    ---@type string[]
-    ensure_installed = require("lsp"):language_servers(),
-})
+local function setup()
+    require("mason-lspconfig").setup({
+        -- A list of servers to automatically install if they're not already installed. Example: { "rust_analyzer@nightly", "lua_ls" }
+        -- This setting has no relation with the `automatic_installation` setting.
+        ---@type string[]
+        ensure_installed = require("lsp"):language_servers(),
+    })
+end
+
+return setup