feat(lsp): refactor

* Move configs into config subdirectory
 * Move LSP logic into classes
 * Make it possible to define mason package in lsp config,
   including nested dependency resolution and post install
   steps
 * replace jedi_language_server with pylsp

lua/lsp/config/bashls.lua

@@ -0,0 +1,21 @@
+return {
+    enable = true,
+    dependencies = {
+        "npm",
+    },
+    mason = {
+        name = "bash-language-server",
+        dependencies = {
+            { name = "shellcheck", },
+        },
+    },
+    lspconfig = {
+        filetypes = {
+            "sh",
+            "bash",
+            "zsh",
+        },
+        cmd = { "bash-language-server", "start", },
+        single_file_support = true,
+    },
+}