Ensure that RocksDB databases open the absolute path

[holtgrewe]

Is your feature request related to a problem? Please describe.
In many places, using symlinks is a useful method for quick/atomic changing of file system resources.

Describe the solution you'd like
For doing multiple symlink changes in the background, we need to open paths behind the symlinks, though. Use read_link to resolve any symlinks to their absolute directory, support a maximal recursion limit of 20.

Describe alternatives you've considered
N/A

Additional context

• https://doc.rust-lang.org/std/fs/fn.read_link.html