[5.0] Better error reporting on snapshot load exceptions

[heifner]

./nodeos --data-dir dd --config-dir mainconfig --snapshot snapshot-2024-02-08-04-eos-v6-0356339018.bin.zst

Before:

warn  2024-03-08T13:37:03.489 nodeos    chain_plugin.cpp:1102         plugin_initialize    ] 3240000 snapshot_exception: Snapshot exception
Binary snapshot validation threw IO exception (Snapshot exception)
    {"what":"Snapshot exception"}
    nodeos  snapshot.cpp:261 validate

appbase: exception thrown during plugin "" initialization.
Snapshot exception

With this PR:

warn  2024-03-08T13:39:02.560 nodeos    snapshot.cpp:260              validate             ] 3240000 snapshot_exception: Snapshot exception
Binary snapshot has unexpected magic number!
    {}
    nodeos  snapshot.cpp:249 validate

warn  2024-03-08T13:39:02.561 nodeos    chain_plugin.cpp:1102         plugin_initialize    ] 3240000 snapshot_exception: Snapshot exception
Binary snapshot has unexpected magic number!
    {}
    nodeos  snapshot.cpp:249 validate
rethrow
    {}
    nodeos  snapshot.cpp:260 validate

appbase: exception thrown during plugin "" initialization.
Snapshot exception

Resolves #2293

[ericpassmore]

Note:start
group: CLEANCODE
category: INTERNALS
summary: More verbose error reporting on snapshot load exceptions.
Note:end

[ericpassmore]

Note:start
category: Logging
component: Internal
summary: More verbose error reporting on snapshot load exceptions.
Note:end