Various small refactoring and fixes in `marconi-mamba`

[koslambrou]

• Remove the --utxo-db CLI parameter in favor of --utxo-db-fname which takes the file name instead of the full path

• Added a CLI param (--db-dir) for specifiying the directory in which to store the SQLite database files.

• Providing target addresses in the CLI through --addresses-to-index is now optional

• Querying the UTXOs for a given address does not limit the address to the target addresses provided in the CLI.

• Fixed the resuming capability of the indexers in marconi-mamba

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• Branch
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• PR
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