Move lsp config to local file structure

.config/nvim/lsp/solidity_ls.lua

@@ -0,0 +1,28 @@
+---@brief
+---
+--- https://github.com/juanfranblanco/vscode-solidity
+---
+--- `vscode-solidity-server` can be installed via `npm`:
+---
+--- ```sh
+--- npm install -g vscode-solidity-server
+--- ```
+---
+--- `vscode-solidity-server` is a language server for the Solidity language ported from the VSCode "solidity" extension.
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'vscode-solidity-server', '--stdio' },
+  filetypes = { 'solidity' },
+  root_markers = {
+    'hardhat.config.js',
+    'hardhat.config.ts',
+    'foundry.toml',
+    'remappings.txt',
+    'truffle.js',
+    'truffle-config.js',
+    'ape-config.yaml',
+    '.git',
+    'package.json',
+  },
+}