Serialize IDs as integers and not strings in PersistedSnapshot

[hiltontj]

The PersistedSnapshot type is serializing the DbId and TableId keys in the databases/tables map as strings. It should instead serialize as a an array of structs, then deserializing as the map with integer keys.

[hiltontj]

See:

influxdb/influxdb3_id/src/serialize.rs

Line 32 in f745ea6

pub struct SerdeVecMap<K: Eq + std::hash::Hash, V>(IndexMap<K, V>);