Add chain properties to chain-spec-builder (#7368)

This PR adds support for chain properties to `chain-spec-builder`. Now
properties can be specified as such:

```sh
$ chain-spec-builder create -r $RUNTIME_PATH --properties tokenSymbol=DUMMY,tokenDecimals=6,isEthereum=false
```

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Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Michal Kucharczyk <1728078+michalkucharczyk@users.noreply.github.com>