`ir_datasets` writes to `$HOME` which makes reproducibility hard

**Describe the bug**

Importing `ir_datasets` requires writing to `$HOME`. Perhaps this is common sense in python land but I have been slightly alienated by this. I expected it to install all their files at installation time and not at runtime because doing it at runtime will result in undefined behavior. Getting rid of this behavior is always hard because I end up patching the actual code when building it with nix such that it doesn't write to places that are not supposed to be written to.

**Expected behavior**

It would be nice if `ir_datasets` would not write to `$HOME` silently but perhaps already installs all their files during installation.

**Additional context**

Please excuse me initially quite harsh text, I wasn't intending to sound aggressive.