Switch to dedicated Python extensions as now recommended

Author: eliericha

.vscode/extensions.json

@@ -2,6 +2,7 @@
    "recommendations": [
       "ms-python.black-formatter",
       "ms-python.flake8",
+      "ms-python.mypy-type-checker",
       "editorconfig.editorconfig",
       "dbaeumer.vscode-eslint",
       "esbenp.prettier-vscode",

.vscode/settings.json.tmpl

@@ -18,11 +18,7 @@
       "editor.tabSize": 3
    },
    "python.analysis.extraPaths": ["testsuite"],
-   "python.linting.enabled": true,
-   "python.linting.mypyEnabled": true,
-   "python.linting.flake8Enabled": true,
    "flake8.args": ["--max-line-length", "88"],
-   "python.formatting.provider": "black",
    "[python]": {
       // Use the same line length as black and flake8
       "vim.textwidth": 88