Daemonize snapshot-converter (#1887)

# Description

This PR add the feature for snapshot-converter to run as a daemon. See
the help text of
```console
$ cabal run snapshot-converter -- --help
Utility for converting snapshots among the different snapshot formats used by
cardano-node.

Usage: snapshot-converter (
                            (--monitor-lsm-snapshots-in ARG --lsm-database ARG |
                              --monitor-lmdb-snapshots-in ARG)
                            --output-mem-snapshots-in ARG |
                            (--input-lsm-snapshot ARG --input-lsm-database ARG |
                              --input-mem ARG | --input-lmdb ARG)
                            (--output-lsm-snapshot ARG
                              --output-lsm-database ARG |
                              --output-mem ARG | --output-lmdb ARG))
                          --config PATH [--threshold THRESHOLD]

  # Running in oneshot mode

      `snapshot-converter` can be invoked to convert a single snapshot to a different
      format. The three formats supported at the moment are: Mem, LMDB and LSM.

      As snapshots in Mem and LMDB are fully contained in one directory, providing
      that one is enough. On the other hand, converting an LSM snapshot requires a
      reference to the snapshot directory as well as the LSM database directory.

      To run in oneshot mode, you have to provide input and output parameters as in:
      ```
      # mem to lsm
      $ snapshot-converter --input-mem <PATH> --output-lsm-snapshot <PATH> --output-lsm-database <PATH> --config <PATH>
      # mem to lmdb
      $ snapshot-converter --input-mem <PATH> --output-lmdb <PATH> --config <PATH>

      # lmdb to lsm
      $ snapshot-converter --input-lmdb <PATH> --output-lsm-snapshot <PATH> --output-lsm-database --config <PATH>
      # lmdb to mem
      $ snapshot-converter --input-lmdb <PATH> --output-mem <PATH> --config <PATH>

      # lsm to mem
      $ snapshot-converter --input-lsm-snapshot <PATH> --input-lsm-database <PATH> --output-mem <PATH> --config <PATH>
      # lsm to mem
      $ snapshot-converter --input-lsm-snapshot <PATH> --input-lsm-database <PATH> --output-lmdb <PATH> --config <PATH>
      ```

      Note that the input and output paths need to be named after the slot number
      of the contained ledger state, this means for example that a snapshot for
      slot 100 has to be contained in a directory `100[_suffix]` and has to be
      written to a directory `100[_some_other_suffix]`. Providing a wrong slot
      number will throw an error.

      This naming convention is the same expected by `cardano-node`.

  # Running in daemon mode

      `snapshot-converter` can be invoked as a daemon to monitor and convert
      snapshots produced by a `cardano-node` into Mem format as they are
      written by the node. This is only meaningful to run if your node
      produces LMDB or LSM snapshots:

      ```
      # lsm to mem
      $ snapshot-converter --monitor-lsm-snapshots-in <PATH> --lsm-database <PATH> --output-mem-snapshots-in <PATH> --config <PATH>
      # lmdb to mem
      $ snapshot-converter --monitor-lmdb-snapshots-in <PATH> --output-mem-snapshots-in <PATH> --config <PATH>
      ```

Available options:
  --config PATH            Path to config file
  --threshold THRESHOLD    PBftSignatureThreshold
  -h,--help                Show this help text
```

Author: jasagredo

ouroboros-consensus-cardano/app/snapshot-converter.hs

@@ -179,6 +179,39 @@ library
     these ^>=1.2,
     validation,
 
+library unstable-snapshot-conversion
+  import: common-lib
+  visibility: public
+  hs-source-dirs: src/unstable-snapshot-conversion
+  other-modules:
+    Ouroboros.Consensus.Cardano.StreamingLedgerTables
+
+  exposed-modules:
+    Ouroboros.Consensus.Cardano.SnapshotConversion
+
+  build-depends:
+    ansi-terminal,
+    base,
+    cardano-ledger-binary,
+    cardano-ledger-core,
+    cardano-ledger-shelley,
+    cborg,
+    directory,
+    filepath,
+    fs-api,
+    microlens,
+    mtl,
+    ouroboros-consensus:{ouroboros-consensus, ouroboros-consensus-lmdb, ouroboros-consensus-lsm},
+    ouroboros-consensus-cardano,
+    random,
+    resource-registry,
+    serialise,
+    sop-core,
+    sop-extras,
+    strict-sop-core,
+    terminal-progress-bar,
+    text,
+
 library unstable-byronspec
   import: common-lib
   visibility: public
@@ -692,37 +725,21 @@ executable immdb-server
 executable snapshot-converter
   import: common-exe
   hs-source-dirs: app
-  other-modules:
-    Ouroboros.Consensus.Cardano.StreamingLedgerTables
-
   main-is: snapshot-converter.hs
   build-depends:
-    ansi-terminal,
     base,
     cardano-crypto-class,
-    cardano-ledger-binary,
-    cardano-ledger-core,
-    cardano-ledger-shelley,
-    cborg,
-    directory,
     filepath,
-    fs-api,
-    microlens,
+    fsnotify,
     mtl,
     optparse-applicative,
-    ouroboros-consensus:{ouroboros-consensus, ouroboros-consensus-lmdb, ouroboros-consensus-lsm},
-    ouroboros-consensus-cardano,
-    ouroboros-consensus-cardano:unstable-cardano-tools,
-    random,
-    resource-registry,
-    serialise,
-    sop-core,
-    sop-extras,
-    strict-sop-core,
-    terminal-progress-bar,
-    text,
+    ouroboros-consensus,
+    ouroboros-consensus-cardano:{ouroboros-consensus-cardano, unstable-cardano-tools, unstable-snapshot-conversion},
     with-utf8,
 
+  if impl(ghc <9.12)
+    build-depends:
+      text
   other-modules:
     DBAnalyser.Parsers