Stop namadan if --path checksum does not match --hash

[Rigorously]

Several validators failed to upgrade from v0.45.1 to v0.46, because they supplied a HTML file (wget github page) instead of JSON file.

After running namadan-0.46.0 ledger run --height 182000 --path $MIGRATION_JSON --hash acadd7d124804448b3c7f7b3dc0c3bc536fe6dbd1594757d5a992d47ecacc5c6 their nodes came in an inconsistent state and they need to sync from scratch. This could perhaps be prevented by having namadan verify the $MIGRATION_JSON.

[brentstone]

@grarco @tzemanovic

[tzemanovic]

if the hash doesn't match the migration file the node will crash with:

The application panicked (crashed).
Message:  called `Result::unwrap()` on an `Err` value:
   0: Provided hash did not match the contents at the specified path.

so the issue is somewhere else

[Rigorously]

The crash because of the hash mismatch implies a restart, and restarts currently cause a panic because the state cannot be restored: #4112 .