Cyphernode on exFAT: several errors

[Kexkey]

Two problems:

1. exFAT doesn't support user permissions or file ownership. We need to run Cyphernode as "current user" instead of "dedicated user" when setting it up;
2. exFAT doesn't support having certain characters in file names; : is one of those. During setup, Cyphernode will make a copy of existing config files before generating new ones, adding the timestamp to the name which contains the colon chars.

Sol. to 1: if we can detect current filesystem (no idea if possible), we should require using current user as the cyphernode user.

Sol. to 2: we need to change the timestamp format and avoid using : or any character not supported by exFAT.

[Kexkey]

Looks like PostgreSQL (at least on Linux) requires changing some file ownership (at least in the official Docker container):

cyphernode_postgres.1.isrgsxyzja5c@debian01    | chmod: changing permissions of '/var/run/postgresql': Operation not permitted
cyphernode_postgres.1.isrgsxyzja5c@debian01    | The files belonging to this database system will be owned by user "postgres".
cyphernode_postgres.1.isrgsxyzja5c@debian01    | This user must also own the server process.
...

Not sure there's a lot we can do about it there...