## Purpose
Implement `getTables` which is used to extract metadata about the
database
## Changes
- Implement `JDBC4DatabaseMetaData's` `getTables` method
- Extract `JDBC4ResultSet` as field in `JDBC4PreparedStatement`
## Related Issue
https://github.com/tursodatabase/limbo/issues/615Closes#1687
OwnedValue has become a powerhouse of madness, mainly because I decided
to do it like that when I first introduced AggContext. I decided it was
enough and I introduced a `Register` struct that contains `OwnedValue`,
`Record` and `Aggregation`, this way we don't use `OwnedValue` for
everything make everyone's life harder.
This is the next step towards making ImmutableRecords the default
because I want to remove unnecessary allocations. Right now we clone
OwnedValues when we generate a record more than needed.
We currently have two value types, `Value` and `OwnedValue`. The
original thinking was that `Value` is external type and `OwnedValue` is
internal type. However, this just results in unnecessary transformation
between the types as data crosses the Limbo library boundary.
Let's just follow SQLite here and consolidate on a single value type
(where `sqlite3_value` is just an alias for the internal `Mem` type).
The way this will eventually work is that we can have bunch of
pre-allocated `OwnedValue` objects in `ProgramState` and basically
return a reference to them all the way to the application itself, which
extracts the actual value.
## Changes
- AS-IS
- `LimboConnection` implements `Connection`
- `JDBC4Connection` implements `LimboConnection`
- TO-BE
- `LimboConnection` doesn't implement `Connection`. It is used to
represent connection to limbo only.
- `JDBC4Connection` implements `Connection` directly. Holds
`LimboConnection` in member field.
- This helps remove the complexity of java's `Connection` interface away
from `LimboConnection`. We can focus on implementing limbo's feature
inside `LimboConnection` and let `JDBC4Connection` handle the
interoperability with jdbc world.
## Reference
https://github.com/tursodatabase/limbo/issues/615Closes#916
## Purpose of this PR
- Remove `AbstractDB` and put limbo db related methods into `LimboDB`
## Changes
- Remove `AbstractDB`
- Implement `close()`
## Reference
- [Issue](https://github.com/tursodatabase/limbo/issues/615)
Closes#946
