[EXPLORE] Give a writeable directory to extensions that want to write files

[deemp]

Some extensions want to write files which is impossible because the Nix store is read-only.

Certain extensions can be patched so that they don't need to write files at runtime. Example: https://github.com/NixOS/nixpkgs/blob/3db62f7b902dd83ff345ea2feee1a35e0980d9b0/pkgs/applications/editors/vscode/extensions/ms-dotnettools.csdevkit/default.nix#L134

In this issue, I consider extensions that want to write files at runtime.

A solution is as follows.

One can symlink the directory that an extension expects to be writeable to /home/<user>/....

#79 shows an example of such a link.

The linked directory path and content should probably be managed via Home Manager.

TODO

• Get a list of extensions that want to write files at runtime. Candidates:
  • Some extensions b*tch about not being able to write into the extensions directory #46
  • Fix ltex-plus.vscode-ltex-plus #123
• Select extensions for which all necessary files can't be written at build time.
• Try the suggested approach with them.
• Research other approaches that don't depend on Home Manager (e.g., FHS).