Install zellkonverter env as rstudio user

[jashapiro]

This PR is a partial fix to #972

I updated the Dockerfile for the cell-type-wilms-tumor-06 module to install zellkonverter packages as the rstudio user. This allows both the rstudio user and root to have access to the installed files, and prevents the lockfile permissions issue that we were seeing.

When running R from the terminal, this seems to solve the zellkonverter problem, and everything works as expected.

However, when running zellkonverter::readH5AD() (or a basilisk::basiliskStart()) in the RStudio console, I now get the following error:

Error in py_module_import(module, convert = convert) : 
  ImportError: /usr/lib/x86_64-linux-gnu/libssl.so.3: version `OPENSSL_3.2.0' not found (required by /usr/share/basilisk/1.16.0/zellkonverter/1.14.1/zellkonverterAnnDataEnv-0.10.6/lib/python3.12/site-packages/h5py/../../.././libcurl.so.4) 

This can be avoided by running Sys.unsetenv("BASILISK_EXTERNAL_DIR") and reinstalling the zellkonverter environment, so I suspect that the RStudio startup is somehow setting something differently from R in the terminal, but I can't yet figure out what that might be.