Motivation for this change

There are currently two open PRs to update bitwarden_rs to version 1.13.0:

• bitwarden_rs: 1.9.1 -> 1.13.0 #74927: Still has some feedback that has not been taken into account.
• bitwarden_rs: 1.9.1 -> 1.13.0 #76673: Only updates the package, not the module, while some people indicated they would want to use the new feature of 1.13 that allows for different database backends.

Now that version 1.13.1 has been released and both PRs seem to have stagnated a bit, as the maintainer I thought it best update to this latest version and take the feedback from the other PRs into account, to hopefully finally get the version bump pushed.

Besides the version update and the corresponding changes needed to be made to the module, I also changed the way I handled the defaults, because checking for the config before it was converted to its normalized environment variable style, could lead to a problem when e.g. webVaultEnabled is checked, while the user set it with WEB_VAULT_ENABLED.

I also changed the backup service type to oneshot, because if I start it manually I expect it to have finished the backup once completed, but I don't believe it should matter much outside this. Please correct me if I am wrong.

I have only tested it in so far that I have been using it myself.

cc: @filalex77 @dali99 @Ma27 @Mic92 @bbigras

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.