Replace coc-pyright because of performance issues

coc-pyright is often stuck at 100% CPU for minutes when it encounters
certain functions, probably while generating inlay type hints.
(see fannheyward/coc-pyright#1087)

pyright itself doesn't provide these hints (MS keeps that feature hidden
in the closed-source pylance VS Code extension), but the fork
basedpyright does. Performance has been good so far, so switch to using
that language server directly from coc.nvim

coc-pyright also handled linting / formatting via e.g. ruff, so that
functionality needs to be replaced as well.

efm-languageserver acts like a proxy between LSP clients and linting /
formatting tools. Multiple tools can be configured per language to
provide linting suggestions or formatting files.

coc.nvim is okay with running multiple language servers for a filetype,
so basedpyright and efm-languageserver can be used together.

home/.config/efm-langserver/config.yaml

@@ -0,0 +1,18 @@
+version: 2
+root-markers:
+  - .git/
+  - .hg/
+lint-debounce: 1s
+
+tools:
+  python-ruff: &python-ruff
+    lint-command: "ruff check --stdin-filename ${INPUT} --output-format concise --quiet -"
+    lint-stdin: true
+    lint-formats:
+      - "%f:%l:%c: %m"
+    format-command: "ruff format --stdin-filename ${INPUT} --quiet -"
+    format-stdin: true
+
+languages:
+  python:
+    - <<: *python-ruff

home/.vim/coc-settings.json

@@ -23,6 +23,16 @@
             "args": [],
             "initializationOptions": {}
         },
+        "linting": {
+            "command": "efm-langserver",
+            "args": [],
+            "filetypes": ["python"]
+        },
+        "python": {
+            "command": "basedpyright-langserver",
+            "args": ["--stdio"],
+            "filetypes": ["python"]
+        },
         "haskell": {
             "command": "haskell-language-server-wrapper",
             "args": ["--lsp"],
@@ -35,8 +45,5 @@
 
     "elixir.pathToElixirLS": "/usr/local/bin/elixir-ls",
 
-    "python.pythonPath": "python3",
-    "python.formatting.provider": "ruff",
-
     "rust.clippy_preference": "on"
 }