Use a hydra-chess specific XDG config/cache directory

[ch1bo]

Why

The README instructions suggest that hydra-chess uses a ~/.config and ~/.cache directory that is only scoped with hydra-node name. As this repository strives to be a good example application, any copies and multiple similar game applications would easily conflict.

What

Use a hydra-chess prefix in the XDG directories and somewhat obvious in the code where this can be changed to, e.g. by an applicationName CAF or inject the project name somehow.

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This surfaced when we reviewed the initial README.md instructions of this repository; #1