Dal: initialize parameters in external block validator as well

Fixes #4268 (closed).

It was simpler to move the dal_config into the ``Cryptobox modulelib_crypto_dal` library, than to try to keep it in `lib_node_config` and update (or mess up) the library dependencies. It could be useful as well if a similar initialization needs to be done elsewhere (like in the baker).

Checklist

• [n/a] Document the interface of any function added or modified (see the coding guidelines)
• [n/a] Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
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